Add WASM SEGV handler and test. #26
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Continuing discussion from the previous PR, this Exception it isn't caught, see:
[2019-02-21 01:05:30.146][2704][error][wasm] [source/extensions/common/wasm/wasm.cc:796] wasm log: before badptr
[2019-02-21 01:05:30.146][2704][critical][main] [source/exe/terminate_handler.cc:13] std::terminate called! (possible uncaught exception, see trace)
[2019-02-21 01:05:30.146][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:67] Backtrace (use tools/stack_decode.py to get line numbers):
[2019-02-21 01:05:30.173][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:73] #0: Envoy::TerminateHandler::logOnTerminate()::$_0::operator()() [0x27464ef]
[2019-02-21 01:05:30.190][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:73] #1: Envoy::TerminateHandler::logOnTerminate()::$_0::__invoke() [0x2746489]
[2019-02-21 01:05:30.207][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:73] #2: __cxxabiv1::__terminate() [0x27ea0c6]
[2019-02-21 01:05:30.207][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:81] Caught Aborted, suspect faulting address 0x3e800000a89
[2019-02-21 01:05:30.207][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:67] Backtrace (use tools/stack_decode.py to get line numbers):
[2019-02-21 01:05:30.224][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:73] #0: Envoy::SignalAction::sigHandler() [0x2743cfc]
[2019-02-21 01:05:30.224][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:73] #1: __restore_rt [0x7f246a03e0c0]
[2019-02-21 01:05:30.224][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:73] #2: Envoy::TerminateHandler::logOnTerminate()::$_0::__invoke() [0x2746489]
[2019-02-21 01:05:30.224][2704][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:73] #3: __cxxabiv1::__terminate() [0x27ea0c6]
Also, I believe that using Runtime::catchRuntimeExceptions() will produce in-module stacktrace vs in-host stacktrace (when using Exceptions), but my memory is a bit fuzzy at this point, so I might be misremembering things.
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| // NOLINT(namespace-envoy) | |||
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You need to add segv.wasm and segv.wat to this commit.
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How can I reproduce the failure you are seeing? When I run bazel test wasm_test in envoy/test/extensions/wasm I get:
//test/extensions/wasm:wasm_test PASSED in 2.4s
Which is to say I am seeing the Exception caught.
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Yes, it works fine in mocked tests (since you're explicitly catching Exception using EXPECT_THROW_WITH_MESSAGE), but that has nothing to do with "normal" usage.
To reproduce that stacktrace, you can add badptr code to any WASM HTTP filter (e.g. headers.cc), recompile it, and start Envoy with it. Envoy should crash when executing badptr code.
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Ah, yes, from the unhandled Exception. I was thinking that generally we would convert all errors of this type to Exceptions so that we can catch them and signal the controller (istio) then unload/disable the filter but I haven't completed that code yet. I was expecting to do it in a later PR. I can capture the stack pointer/trace when I throw the Exception as well. That should generalize to this case as well as those covered by Runtime::catchRuntimeExceptions(). Do you have another design in mind. Let's talk offline.
While there, re-enable make/free accounting, since it was broken for the same reason (implementation was leaked into headers). Fixes envoyproxy/envoy-wasm#18. Signed-off-by: Piotr Sikora <piotrsikora@google.com>
Add WASM SEGV handler and test.
When llvm detects that an trap is inevitable it calls the function llvm_trap.
This provides a handler which converts the crash into an Exception which can be caught.