SIGSEGV crash when using client upstream #791
Description
I'm getting a crash when I have a client upstream dns provider configured, as soon as the client makes a dns request. When I disable the client entry, there's no crash. The issue exists in v0.19, v0.20 and development Docker images.
The upstream configuration is basically (values redacted):
upstream:
default:
- 8.8.8.8
- 9.9.9.9
1.2.3.4:
- https://family.cloudflare-dns.com/dns-queryIt does not matter if I change the upstream provider. However, after some experimentation, it does seem to be fixed if I add a second entry, as in:
upstream:
default:
- 8.8.8.8
- 9.9.9.9
1.2.3.4:
- https://family.cloudflare-dns.com/dns-query
- 1.1.1.3I also have customDNS.mapping and condition.mapping configurations, if those are relevant. But simply commenting out the client upstream, or adding the second provider, stops the crashing.
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x88e200]
goroutine 476 [running]:
github.com/0xERR0R/blocky/resolver.weightedRandom({0x28676d8, 0x2, 0x2}, {0xbd1184, 0x266e150})
/go/src/resolver/parallel_best_resolver.go:244 +0x360
github.com/0xERR0R/blocky/resolver.pickRandom({0x28676d8, 0x2, 0x2})
/go/src/resolver/parallel_best_resolver.go:215 +0x70
github.com/0xERR0R/blocky/resolver.(*ParallelBestResolver).Resolve(0x271a550, 0x28065c0)
/go/src/resolver/parallel_best_resolver.go:175 +0xf4
github.com/0xERR0R/blocky/resolver.(*SpecialUseDomainNamesResolver).Resolve(0x33129d0, 0x28065c0)
/go/src/resolver/sudn_resolver.go:78 +0x310
github.com/0xERR0R/blocky/resolver.(*ConditionalUpstreamResolver).Resolve(0x3312720, 0x28065c0)
/go/src/resolver/conditional_upstream_resolver.go:95 +0x254
github.com/0xERR0R/blocky/resolver.(*CachingResolver).Resolve(0x2715380, 0x28065c0)
/go/src/resolver/caching_resolver.go:204 +0x630
github.com/0xERR0R/blocky/resolver.(*BlockingResolver).Resolve(0x2462680, 0x28065c0)
/go/src/resolver/blocking_resolver.go:419 +0x16c
github.com/0xERR0R/blocky/resolver.(*HostsFileResolver).Resolve(0x266e450, 0x28065c0)
/go/src/resolver/hosts_file_resolver.go:70 +0x2c8
github.com/0xERR0R/blocky/resolver.(*CustomDNSResolver).Resolve(0x26c2cf0, 0x28065c0)
/go/src/resolver/custom_dns_resolver.go:157 +0x268
github.com/0xERR0R/blocky/resolver.(*MetricsResolver).Resolve(0x266e420, 0x28065c0)
/go/src/resolver/metrics_resolver.go:28 +0x30
github.com/0xERR0R/blocky/resolver.(*QueryLoggingResolver).Resolve(0x266e2a0, 0x28065c0)
/go/src/resolver/query_logging_resolver.go:109 +0x108
github.com/0xERR0R/blocky/resolver.(*EdeResolver).Resolve(0x3312760, 0x28065c0)
/go/src/resolver/ede_resolver.go:21 +0x30
github.com/0xERR0R/blocky/resolver.(*ClientNamesResolver).Resolve(0x266e1e0, 0x28065c0)
/go/src/resolver/client_names_resolver.go:79 +0x188
github.com/0xERR0R/blocky/resolver.(*FqdnOnlyResolver).Resolve(0x3312750, 0x28065c0)
/go/src/resolver/fqdn_only_resolver.go:34 +0x120
github.com/0xERR0R/blocky/resolver.(*FilteringResolver).Resolve(0x3312740, 0x28065c0)
/go/src/resolver/filtering_resolver.go:29 +0x1fc
github.com/0xERR0R/blocky/server.(*Server).OnRequest(0x2462800, {0xbd6d78, 0x2806500}, 0x26cb630)
/go/src/server/server.go:617 +0xdc
github.com/miekg/dns.HandlerFunc.ServeDNS(0x327e1c8, {0xbd6d78, 0x2806500}, 0x26cb630)
/go/pkg/mod/github.com/miekg/dns@v1.1.50/server.go:37 +0x34
github.com/miekg/dns.(*ServeMux).ServeDNS(0x2400080, {0xbd6d78, 0x2806500}, 0x26cb630)
/go/pkg/mod/github.com/miekg/dns@v1.1.50/serve_mux.go:103 +0x90
github.com/miekg/dns.(*Server).serveDNS(0x247a000, {0x332a000, 0x24, 0xffff}, 0x2806500)
/go/pkg/mod/github.com/miekg/dns@v1.1.50/server.go:659 +0x454
github.com/miekg/dns.(*Server).serveUDPPacket(0x247a000, 0x2850070, {0x332a000, 0x24, 0xffff}, {0xbd5d70, 0x271a008}, 0x29a7fe0, {0x0, 0x0})
/go/pkg/mod/github.com/miekg/dns@v1.1.50/server.go:603 +0x1c8
created by github.com/miekg/dns.(*Server).serveUDP
/go/pkg/mod/github.com/miekg/dns@v1.1.50/server.go:533 +0x48c