small cleanup in CREDITS #12
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I believe pull requests like this are not used. https://github.com/torvalds/linux/blob/master/Documentation/HOWTO I recommend reading that. |
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Thanks Gunni! Now that I have read my way through the documentation, three small questions before I close this:
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This is considered a trivial patch. Please consult |
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Well, according to https://github.com/torvalds/linux/blob/master/Documentation/SubmittingPatches#L200 you should mail Jiri Kosina trivial@kernel.org. https://github.com/torvalds/linux/blob/master/MAINTAINERS#L6515 However since kernel.org is down i can not say where this should be sent, maybe use vger as a replacement and note that you're mailing there because the correct mail is down. EDIT: yeah or use the mail sc68cal submitted: Jiri Kosina jkosina@suse.cz. |
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Thanks a lot! I'll email my patch to Jiri Kosina. |
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You also need to amend your commit message to add a sign off line. You need that in the commit message or your patch will not be accepted. Check the docs for more info |
torvalds
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Nov 3, 2011
When the cgroup base was allocated with kmalloc, it was necessary to annotate the variable with kmemleak_not_leak(). But because it has recently been changed to be allocated with alloc_page() (which skips kmemleak checks) causes a warning on boot up. I was triggering this output: allocated 8388608 bytes of page_cgroup please try 'cgroup_disable=memory' option if you don't want memory cgroups kmemleak: Trying to color unknown object at 0xf5840000 as Grey Pid: 0, comm: swapper Not tainted 3.0.0-test #12 Call Trace: [<c17e34e6>] ? printk+0x1d/0x1f^M [<c10e2941>] paint_ptr+0x4f/0x78 [<c178ab57>] kmemleak_not_leak+0x58/0x7d [<c108ae9f>] ? __rcu_read_unlock+0x9/0x7d [<c1cdb462>] kmemleak_init+0x19d/0x1e9 [<c1cbf771>] start_kernel+0x346/0x3ec [<c1cbf1b4>] ? loglevel+0x18/0x18 [<c1cbf0aa>] i386_start_kernel+0xaa/0xb0 After a bit of debugging I tracked the object 0xf840000 (and others) down to the cgroup code. The change from allocating base with kmalloc to alloc_page() has the base not calling kmemleak_alloc() which adds the pointer to the object_tree_root, but kmemleak_not_leak() adds it to the crt_early_log[] table. On kmemleak_init(), the entry is found in the early_log[] but not the object_tree_root, and this error message is displayed. If alloc_page() fails then it defaults back to vmalloc() which still uses the kmemleak_alloc() which makes us still need the kmemleak_not_leak() call. The solution is to call the kmemleak_alloc() directly if the alloc_page() succeeds. Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cuviper
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Nov 3, 2011
* Ingo Molnar <mingo@elte.hu> wrote: > The patch below addresses these concerns, serializes the output, tidies up the > printout, resulting in this new output: There's one bug remaining that my patch does not address: the vCPUs are not printed in order: # vCPU #0's dump: # vCPU #2's dump: # vCPU torvalds#24's dump: # vCPU #5's dump: # vCPU torvalds#39's dump: # vCPU torvalds#38's dump: # vCPU torvalds#51's dump: # vCPU torvalds#11's dump: # vCPU torvalds#10's dump: # vCPU torvalds#12's dump: This is undesirable as the order of printout is highly random, so successive dumps are difficult to compare. The patch below serializes the signalling itself. (this is on top of the previous patch) The patch also tweaks the vCPU printout line a bit so that it does not start with '#', which is discarded if such messages are pasted into Git commit messages. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Pekka Enberg <penberg@kernel.org>
torvalds
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Dec 15, 2011
If the pte mapping in generic_perform_write() is unmapped between iov_iter_fault_in_readable() and iov_iter_copy_from_user_atomic(), the "copied" parameter to ->end_write can be zero. ext4 couldn't cope with it with delayed allocations enabled. This skips the i_disksize enlargement logic if copied is zero and no new data was appeneded to the inode. gdb> bt #0 0xffffffff811afe80 in ext4_da_should_update_i_disksize (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x1\ 08000, len=0x1000, copied=0x0, page=0xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2467 #1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\ xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512 #2 0xffffffff810d97f1 in generic_perform_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value o\ ptimized out>, pos=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2440 #3 generic_file_buffered_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value optimized out>, p\ os=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2482 #4 0xffffffff810db5d1 in __generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, ppos=0\ xffff88001e26be40) at mm/filemap.c:2600 #5 0xffffffff810db853 in generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=<value optimi\ zed out>, pos=<value optimized out>) at mm/filemap.c:2632 #6 0xffffffff811a71aa in ext4_file_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, pos=0x108000) a\ t fs/ext4/file.c:136 #7 0xffffffff811375aa in do_sync_write (filp=0xffff88003f606a80, buf=<value optimized out>, len=<value optimized out>, \ ppos=0xffff88001e26bf48) at fs/read_write.c:406 #8 0xffffffff81137e56 in vfs_write (file=0xffff88003f606a80, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x4\ 000, pos=0xffff88001e26bf48) at fs/read_write.c:435 #9 0xffffffff8113816c in sys_write (fd=<value optimized out>, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x\ 4000) at fs/read_write.c:487 #10 <signal handler called> #11 0x00007f120077a390 in __brk_reservation_fn_dmi_alloc__ () #12 0x0000000000000000 in ?? () gdb> print offset $22 = 0xffffffffffffffff gdb> print idx $23 = 0xffffffff gdb> print inode->i_blkbits $24 = 0xc gdb> up #1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\ xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512 2512 if (ext4_da_should_update_i_disksize(page, end)) { gdb> print start $25 = 0x0 gdb> print end $26 = 0xffffffffffffffff gdb> print pos $27 = 0x108000 gdb> print new_i_size $28 = 0x108000 gdb> print ((struct ext4_inode_info *)((char *)inode-((int)(&((struct ext4_inode_info *)0)->vfs_inode))))->i_disksize $29 = 0xd9000 gdb> down 2467 for (i = 0; i < idx; i++) gdb> print i $30 = 0xd44acbee This is 100% reproducible with some autonuma development code tuned in a very aggressive manner (not normal way even for knumad) which does "exotic" changes to the ptes. It wouldn't normally trigger but I don't see why it can't happen normally if the page is added to swap cache in between the two faults leading to "copied" being zero (which then hangs in ext4). So it should be fixed. Especially possible with lumpy reclaim (albeit disabled if compaction is enabled) as that would ignore the young bits in the ptes. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
torvalds
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Feb 8, 2012
Overly indented code should be refactored.
Suggest refactoring excessive indentation of of
if/else/for/do/while/switch statements.
For example:
$ cat t.c
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
if (1)
if (2)
if (3)
if (4)
if (5)
if (6)
if (7)
if (8)
;
return 0;
}
$ ./scripts/checkpatch.pl -f t.c
WARNING: Too many leading tabs - consider code refactoring
#12: FILE: t.c:12:
+ if (6)
WARNING: Too many leading tabs - consider code refactoring
#13: FILE: t.c:13:
+ if (7)
WARNING: Too many leading tabs - consider code refactoring
#14: FILE: t.c:14:
+ if (8)
total: 0 errors, 3 warnings, 17 lines checked
t.c has style problems, please review.
If any of these errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
jkstrick
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Feb 11, 2012
If the netdev is already in NETREG_UNREGISTERING/_UNREGISTERED state, do not update the real num tx queues. netdev_queue_update_kobjects() is already called via remove_queue_kobjects() at NETREG_UNREGISTERING time. So, when upper layer driver, e.g., FCoE protocol stack is monitoring the netdev event of NETDEV_UNREGISTER and calls back to LLD ndo_fcoe_disable() to remove extra queues allocated for FCoE, the associated txq sysfs kobjects are already removed, and trying to update the real num queues would cause something like below: ... PID: 25138 TASK: ffff88021e64c440 CPU: 3 COMMAND: "kworker/3:3" #0 [ffff88021f007760] machine_kexec at ffffffff810226d9 #1 [ffff88021f0077d0] crash_kexec at ffffffff81089d2d #2 [ffff88021f0078a0] oops_end at ffffffff813bca78 #3 [ffff88021f0078d0] no_context at ffffffff81029e72 #4 [ffff88021f007920] __bad_area_nosemaphore at ffffffff8102a155 #5 [ffff88021f0079f0] bad_area_nosemaphore at ffffffff8102a23e torvalds#6 [ffff88021f007a00] do_page_fault at ffffffff813bf32e torvalds#7 [ffff88021f007b10] page_fault at ffffffff813bc045 [exception RIP: sysfs_find_dirent+17] RIP: ffffffff81178611 RSP: ffff88021f007bc0 RFLAGS: 00010246 RAX: ffff88021e64c440 RBX: ffffffff8156cc63 RCX: 0000000000000004 RDX: ffffffff8156cc63 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88021f007be0 R8: 0000000000000004 R9: 0000000000000008 R10: ffffffff816fed00 R11: 0000000000000004 R12: 0000000000000000 R13: ffffffff8156cc63 R14: 0000000000000000 R15: ffff8802222a0000 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 torvalds#8 [ffff88021f007be8] sysfs_get_dirent at ffffffff81178c07 torvalds#9 [ffff88021f007c18] sysfs_remove_group at ffffffff8117ac27 torvalds#10 [ffff88021f007c48] netdev_queue_update_kobjects at ffffffff813178f9 torvalds#11 [ffff88021f007c88] netif_set_real_num_tx_queues at ffffffff81303e38 torvalds#12 [ffff88021f007cc8] ixgbe_set_num_queues at ffffffffa0249763 [ixgbe] torvalds#13 [ffff88021f007cf8] ixgbe_init_interrupt_scheme at ffffffffa024ea89 [ixgbe] torvalds#14 [ffff88021f007d48] ixgbe_fcoe_disable at ffffffffa0267113 [ixgbe] torvalds#15 [ffff88021f007d68] vlan_dev_fcoe_disable at ffffffffa014fef5 [8021q] torvalds#16 [ffff88021f007d78] fcoe_interface_cleanup at ffffffffa02b7dfd [fcoe] torvalds#17 [ffff88021f007df8] fcoe_destroy_work at ffffffffa02b7f08 [fcoe] torvalds#18 [ffff88021f007e18] process_one_work at ffffffff8105d7ca torvalds#19 [ffff88021f007e68] worker_thread at ffffffff81060513 torvalds#20 [ffff88021f007ee8] kthread at ffffffff810648b6 torvalds#21 [ffff88021f007f48] kernel_thread_helper at ffffffff813c40f4 Signed-off-by: Yi Zou <yi.zou@intel.com> Tested-by: Ross Brattain <ross.b.brattain@intel.com> Tested-by: Stephen Ko <stephen.s.ko@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
zachariasmaladroit
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Feb 11, 2012
If the netdev is already in NETREG_UNREGISTERING/_UNREGISTERED state, do not update the real num tx queues. netdev_queue_update_kobjects() is already called via remove_queue_kobjects() at NETREG_UNREGISTERING time. So, when upper layer driver, e.g., FCoE protocol stack is monitoring the netdev event of NETDEV_UNREGISTER and calls back to LLD ndo_fcoe_disable() to remove extra queues allocated for FCoE, the associated txq sysfs kobjects are already removed, and trying to update the real num queues would cause something like below: ... PID: 25138 TASK: ffff88021e64c440 CPU: 3 COMMAND: "kworker/3:3" #0 [ffff88021f007760] machine_kexec at ffffffff810226d9 #1 [ffff88021f0077d0] crash_kexec at ffffffff81089d2d #2 [ffff88021f0078a0] oops_end at ffffffff813bca78 #3 [ffff88021f0078d0] no_context at ffffffff81029e72 #4 [ffff88021f007920] __bad_area_nosemaphore at ffffffff8102a155 #5 [ffff88021f0079f0] bad_area_nosemaphore at ffffffff8102a23e torvalds#6 [ffff88021f007a00] do_page_fault at ffffffff813bf32e torvalds#7 [ffff88021f007b10] page_fault at ffffffff813bc045 [exception RIP: sysfs_find_dirent+17] RIP: ffffffff81178611 RSP: ffff88021f007bc0 RFLAGS: 00010246 RAX: ffff88021e64c440 RBX: ffffffff8156cc63 RCX: 0000000000000004 RDX: ffffffff8156cc63 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88021f007be0 R8: 0000000000000004 R9: 0000000000000008 R10: ffffffff816fed00 R11: 0000000000000004 R12: 0000000000000000 R13: ffffffff8156cc63 R14: 0000000000000000 R15: ffff8802222a0000 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 torvalds#8 [ffff88021f007be8] sysfs_get_dirent at ffffffff81178c07 torvalds#9 [ffff88021f007c18] sysfs_remove_group at ffffffff8117ac27 torvalds#10 [ffff88021f007c48] netdev_queue_update_kobjects at ffffffff813178f9 torvalds#11 [ffff88021f007c88] netif_set_real_num_tx_queues at ffffffff81303e38 torvalds#12 [ffff88021f007cc8] ixgbe_set_num_queues at ffffffffa0249763 [ixgbe] torvalds#13 [ffff88021f007cf8] ixgbe_init_interrupt_scheme at ffffffffa024ea89 [ixgbe] torvalds#14 [ffff88021f007d48] ixgbe_fcoe_disable at ffffffffa0267113 [ixgbe] torvalds#15 [ffff88021f007d68] vlan_dev_fcoe_disable at ffffffffa014fef5 [8021q] torvalds#16 [ffff88021f007d78] fcoe_interface_cleanup at ffffffffa02b7dfd [fcoe] torvalds#17 [ffff88021f007df8] fcoe_destroy_work at ffffffffa02b7f08 [fcoe] torvalds#18 [ffff88021f007e18] process_one_work at ffffffff8105d7ca torvalds#19 [ffff88021f007e68] worker_thread at ffffffff81060513 torvalds#20 [ffff88021f007ee8] kthread at ffffffff810648b6 torvalds#21 [ffff88021f007f48] kernel_thread_helper at ffffffff813c40f4 Signed-off-by: Yi Zou <yi.zou@intel.com> Tested-by: Ross Brattain <ross.b.brattain@intel.com> Tested-by: Stephen Ko <stephen.s.ko@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
tworaz
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Feb 13, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 torvalds#6 [d72d3cb4] isolate_migratepages at c030b15a torvalds#7 [d72d3d1] zone_watermark_ok at c02d26cb torvalds#8 [d72d3d2c] compact_zone at c030b8d torvalds#9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xXorAa
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Feb 17, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 torvalds#6 [d72d3cb4] isolate_migratepages at c030b15a torvalds#7 [d72d3d1] zone_watermark_ok at c02d26cb torvalds#8 [d72d3d2c] compact_zone at c030b8d torvalds#9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
koenkooi
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Feb 23, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Mar 1, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Mar 19, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Mar 22, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Apr 2, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Apr 9, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Apr 11, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
koenkooi
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Apr 12, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
psanford
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to retailnext/linux
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Apr 16, 2012
BugLink: http://bugs.launchpad.net/bugs/907778 commit ea51d13 upstream. If the pte mapping in generic_perform_write() is unmapped between iov_iter_fault_in_readable() and iov_iter_copy_from_user_atomic(), the "copied" parameter to ->end_write can be zero. ext4 couldn't cope with it with delayed allocations enabled. This skips the i_disksize enlargement logic if copied is zero and no new data was appeneded to the inode. gdb> bt #0 0xffffffff811afe80 in ext4_da_should_update_i_disksize (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x1\ 08000, len=0x1000, copied=0x0, page=0xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2467 #1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\ xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512 #2 0xffffffff810d97f1 in generic_perform_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value o\ ptimized out>, pos=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2440 #3 generic_file_buffered_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value optimized out>, p\ os=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2482 #4 0xffffffff810db5d1 in __generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, ppos=0\ xffff88001e26be40) at mm/filemap.c:2600 #5 0xffffffff810db853 in generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=<value optimi\ zed out>, pos=<value optimized out>) at mm/filemap.c:2632 torvalds#6 0xffffffff811a71aa in ext4_file_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, pos=0x108000) a\ t fs/ext4/file.c:136 torvalds#7 0xffffffff811375aa in do_sync_write (filp=0xffff88003f606a80, buf=<value optimized out>, len=<value optimized out>, \ ppos=0xffff88001e26bf48) at fs/read_write.c:406 torvalds#8 0xffffffff81137e56 in vfs_write (file=0xffff88003f606a80, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x4\ 000, pos=0xffff88001e26bf48) at fs/read_write.c:435 torvalds#9 0xffffffff8113816c in sys_write (fd=<value optimized out>, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x\ 4000) at fs/read_write.c:487 torvalds#10 <signal handler called> torvalds#11 0x00007f120077a390 in __brk_reservation_fn_dmi_alloc__ () torvalds#12 0x0000000000000000 in ?? () gdb> print offset $22 = 0xffffffffffffffff gdb> print idx $23 = 0xffffffff gdb> print inode->i_blkbits $24 = 0xc gdb> up #1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\ xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512 2512 if (ext4_da_should_update_i_disksize(page, end)) { gdb> print start $25 = 0x0 gdb> print end $26 = 0xffffffffffffffff gdb> print pos $27 = 0x108000 gdb> print new_i_size $28 = 0x108000 gdb> print ((struct ext4_inode_info *)((char *)inode-((int)(&((struct ext4_inode_info *)0)->vfs_inode))))->i_disksize $29 = 0xd9000 gdb> down 2467 for (i = 0; i < idx; i++) gdb> print i $30 = 0xd44acbee This is 100% reproducible with some autonuma development code tuned in a very aggressive manner (not normal way even for knumad) which does "exotic" changes to the ptes. It wouldn't normally trigger but I don't see why it can't happen normally if the page is added to swap cache in between the two faults leading to "copied" being zero (which then hangs in ext4). So it should be fixed. Especially possible with lumpy reclaim (albeit disabled if compaction is enabled) as that would ignore the young bits in the ptes. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Tim Gardner <tim.gardner@canonical.com> Signed-off-by: Brad Figg <brad.figg@canonical.com>
psanford
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Apr 16, 2012
…S block during isolation for migration BugLink: http://bugs.launchpad.net/bugs/931719 commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 torvalds#6 [d72d3cb4] isolate_migratepages at c030b15a torvalds#7 [d72d3d1] zone_watermark_ok at c02d26cb torvalds#8 [d72d3d2c] compact_zone at c030b8d torvalds#9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
koenkooi
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Apr 19, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
koenkooi
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May 4, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
koenkooi
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May 4, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
koenkooi
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to koenkooi/linux
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May 5, 2012
…S block during isolation for migration commit 0bf380b upstream. When isolating for migration, migration starts at the start of a zone which is not necessarily pageblock aligned. Further, it stops isolating when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally not aligned. This allows isolate_migratepages() to call pfn_to_page() on an invalid PFN which can result in a crash. This was originally reported against a 3.0-based kernel with the following trace in a crash dump. PID: 9902 TASK: d47aecd0 CPU: 0 COMMAND: "memcg_process_s" #0 [d72d3ad0] crash_kexec at c028cfdb #1 [d72d3b24] oops_end at c05c5322 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60 #3 [d72d3bec] bad_area at c0227fb6 #4 [d72d3c00] do_page_fault at c05c72e #5 [d72d3c80] error_code (via page_fault) at c05c47a4 EAX: 00000000 EBX: 000c0000 ECX: 00000001 EDX: 00000807 EBP: 000c0000 DS: 007b ESI: 00000001 ES: 007b EDI: f3000a80 GS: 6f50 CS: 0060 EIP: c030b15a ERR: ffffffff EFLAGS: 00010002 #6 [d72d3cb4] isolate_migratepages at c030b15a #7 [d72d3d1] zone_watermark_ok at c02d26cb #8 [d72d3d2c] compact_zone at c030b8d #9 [d72d3d68] compact_zone_order at c030bba1 torvalds#10 [d72d3db4] try_to_compact_pages at c030bc84 torvalds#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7 torvalds#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7 torvalds#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97 torvalds#14 [d72d3eb8] alloc_pages_vma at c030a845 torvalds#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb torvalds#16 [d72d3f00] handle_mm_fault at c02f36c6 torvalds#17 [d72d3f30] do_page_fault at c05c70ed torvalds#18 [d72d3fb] error_code (via page_fault) at c05c47a4 EAX: b71ff000 EBX: 00000001 ECX: 00001600 EDX: 00000431 DS: 007b ESI: 08048950 ES: 007b EDI: bfaa3788 SS: 007b ESP: bfaa36e0 EBP: bfaa3828 GS: 6f50 CS: 0073 EIP: 080487c8 ERR: ffffffff EFLAGS: 00010202 It was also reported by Herbert van den Bergh against 3.1-based kernel with the following snippet from the console log. BUG: unable to handle kernel paging request at 01c00008 IP: [<c0522399>] isolate_migratepages+0x119/0x390 *pdpt = 000000002f7ce001 *pde = 0000000000000000 It is expected that it also affects 3.2.x and current mainline. The problem is that pfn_valid is only called on the first PFN being checked and that PFN is not necessarily aligned. Lets say we have a case like this H = MAX_ORDER_NR_PAGES boundary | = pageblock boundary m = cc->migrate_pfn f = cc->free_pfn o = memory hole H------|------H------|----m-Hoooooo|ooooooH-f----|------H The migrate_pfn is just below a memory hole and the free scanner is beyond the hole. When isolate_migratepages started, it scans from migrate_pfn to migrate_pfn+pageblock_nr_pages which is now in a memory hole. It checks pfn_valid() on the first PFN but then scans into the hole where there are not necessarily valid struct pages. This patch ensures that isolate_migratepages calls pfn_valid when necessary. Reported-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Tested-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kuba-moo
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to linux-netdev/testing
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Aug 20, 2025
Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Signed-off-by: Jakub Acs <acsjakub@amazon.de> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: security@kernel.org Cc: stable@kernel.org Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: NipaLocal <nipa@local>
kuba-moo
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Aug 20, 2025
Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Signed-off-by: Jakub Acs <acsjakub@amazon.de> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: security@kernel.org Cc: stable@kernel.org Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: NipaLocal <nipa@local>
kuba-moo
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Aug 20, 2025
Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Signed-off-by: Jakub Acs <acsjakub@amazon.de> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: security@kernel.org Cc: stable@kernel.org Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: NipaLocal <nipa@local>
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Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Signed-off-by: Jakub Acs <acsjakub@amazon.de> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: security@kernel.org Cc: stable@kernel.org Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: NipaLocal <nipa@local>
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Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Signed-off-by: Jakub Acs <acsjakub@amazon.de> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: security@kernel.org Cc: stable@kernel.org Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: NipaLocal <nipa@local>
kuba-moo
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Aug 21, 2025
Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org>
mj22226
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Aug 22, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
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to mj22226/linux
that referenced
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Aug 22, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
this pull request
Aug 22, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
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Aug 24, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
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Aug 24, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
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Aug 24, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
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Aug 24, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
this pull request
Aug 24, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
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to mj22226/linux
that referenced
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Aug 24, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
this pull request
Aug 25, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
this pull request
Aug 26, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
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Aug 26, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
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Aug 26, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
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Aug 26, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mj22226
pushed a commit
to mj22226/linux
that referenced
this pull request
Aug 26, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
MatthewCroughan
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to MatthewCroughan/linux
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Aug 28, 2025
Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org>
MatthewCroughan
pushed a commit
to MatthewCroughan/linux
that referenced
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Aug 28, 2025
Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org>
intersectRaven
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Aug 28, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1054009064
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Aug 28, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1054009064
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Aug 28, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1054009064
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Aug 28, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1054009064
pushed a commit
to 1054009064/linux
that referenced
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Aug 28, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1054009064
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Aug 28, 2025
commit 7af76e9 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 torvalds#12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs <acsjakub@amazon.de> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
quasafox
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Aug 30, 2025
Here is the first fix for torvalds#12, which fix the limited cpufreq for schedutil. But it still tend to stay at max cpufreq.
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Hi,
Here is what I did to the
CREDITSfile:Sorry for the microscopic commit.
Sincerely,
Jan.