crash

[hanwen]

https://cs.bazel.build/search?q=register+syncCallback+case%3Ano&num=50

unexpected fault address 0x7fdb75ef1ef1 fatal error: fault [signal SIGSEGV: segmentation violation code=0x1 addr=0x7fdb75ef1ef1 pc=0x571cf6] goroutine 3568545 [running]: runtime.throw(0x93589e, 0x5) /usr/lib/google-golang/src/runtime/panic.go:622 +0x8a fp=0xc530c07228 sp=0xc530c07208 pc=0x54224a runtime.sigpanic() /usr/lib/google-golang/src/runtime/signal_unix.go:395 +0x211 fp=0xc530c07278 sp=0xc530c07228 pc=0x5579d1 runtime.memmove(0xc42083e270, 0x7fdb75ef1ef1, 0xc) /usr/lib/google-golang/src/runtime/memmove_amd64.s:172 +0x136 fp=0xc530c07280 sp=0xc530c07278 pc=0x571cf6 runtime.slicebytetostring(0x0, 0x7fdb75ef1ef1, 0xc, 0x4d10f, 0xc42083e270, 0xc) /usr/lib/google-golang/src/runtime/string.go:98 +0x6f fp=0xc530c072b0 sp=0xc530c07280 pc=0x55c1ef github.com/google/zoekt/web.(Server).formatResults(0xc8ca5a8000, 0xc8a4e8aab0, 0xc71bc56f70, 0xb, 0xc42276ff00, 0xc7d3747200, 0xc8a4e8aab0, 0x0, 0x0, 0 xc707ebeb78) /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/snippets.go:127 +0x29c fp=0xc530c07a70 sp=0xc530c072b0 pc=0x8523dc github.com/google/zoekt/web.(Server).serveSearchErr(0xc8ca5a8000, 0x98a2c0, 0xc7d93be380, 0xc5fb950700, 0x0, 0x0) /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/server.go:244 +0x48e fp=0xc530c07c68 sp=0xc530c07a70 pc=0x84f8be github.com/google/zoekt/web.(Server).serveSearch(0xc8ca5a8000, 0x98a2c0, 0xc7d93be380, 0xc5fb950700) /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/server.go:157 +0x4d fp=0xc530c07cc0 sp=0xc530c07c68 pc=0x84f28d github.com/google/zoekt/web.(Server).(github.com/google/zoekt/web.serveSearch)-fm(0x98a2c0, 0xc7d93be380, 0xc5fb950700) /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/server.go:146 +0x48 fp=0xc530c07cf0 sp=0xc530c07cc0 pc=0x8549f8 net/http.HandlerFunc.ServeHTTP(0xc88e6c68e0, 0x98a2c0, 0xc7d93be380, 0xc5fb950700) /usr/lib/google-golang/src/net/http/server.go:1946 +0x44 fp=0xc530c07d18 sp=0xc530c07cf0 pc=0x7c64d4 net/http.(ServeMux).ServeHTTP(0xc88151bd40, 0x98a2c0, 0xc7d93be380, 0xc5fb950700) /usr/lib/google-golang/src/net/http/server.go:2336 +0x130 fp=0xc530c07d58 sp=0xc530c07d18 pc=0x7c8140 net/http.serverHandler.ServeHTTP(0xc88a00d5f0, 0x98a2c0, 0xc7d93be380, 0xc5fb950700) /usr/lib/google-golang/src/net/http/server.go:2693 +0xbc fp=0xc530c07d88 sp=0xc530c07d58 pc=0x7c917c net/http.(conn).serve(0xc5008774a0, 0x98a740, 0xc89b37d080) /usr/lib/google-golang/src/net/http/server.go:1829 +0x651 fp=0xc530c07fc8 sp=0xc530c07d88 pc=0x7c54f1 runtime.goexit() /usr/lib/google-golang/src/runtime/asm_amd64.s:2361 +0x1 fp=0xc530c07fd0 sp=0xc530c07fc8 pc=0x571351 created by net/http.(Server).Serve /usr/lib/google-golang/src/net/http/server.go:2794 +0x27b goroutine 1 [IO wait]: internal/poll.runtime_pollWait(0x7fdf5b1d0e30, 0x72, 0x0) /usr/lib/google-golang/src/runtime/netpoll.go:173 +0x57 internal/poll.(pollDesc).wait(0xc88b4d1a98, 0x72, 0xc420570000, 0x0, 0x0) /usr/lib/google-golang/src/internal/poll/fd_poll_runtime.go:85 +0x9b internal/poll.(*pollDesc).waitRead(0xc88b4d1a98, 0xffffffffffffff00, 0x0, 0x0) /usr/lib/google-golang/src/internal/poll/fd_poll_runtime.go:90 +0x3d

[hanwen]

this is the line:

            frag := Fragment{
                Pre:   string(line[lastEnd:l]),

maybe the indices are out of bound, but that should not generate segv?

[hanwen]

unexpected fault address 0x7fa52bc92b69 fatal error: fault [signal SIGSEGV: segmentation violation code=0x1 addr=0x7fa52bc92b69 pc=0x5702ca] goroutine 24375608 [running]: runtime.throw(0x93589e, 0x5) /usr/lib/google-golang/src/runtime/panic.go:622 +0x8a fp=0xc78cf1b1e8 sp=0xc78cf1b1c8 pc=0x54224a runtime.sigpanic() /usr/lib/google-golang/src/runtime/signal_unix.go:395 +0x211 fp=0xc78cf1b238 sp=0xc78cf1b1e8 pc=0x5579d1 runtime.aeshashbody() /usr/lib/google-golang/src/runtime/asm_amd64.s:962 +0x5a fp=0xc78cf1b240 sp=0xc78cf1b238 pc=0x5702ca runtime.mapaccess2_faststr(0x8bddc0, 0xc78cf1b430, 0x7fa52bc92b69, 0x8, 0x1, 0xcabeb28a00) /usr/lib/google-golang/src/runtime/hashmap_fast.go:322 +0x1df fp=0xc78cf1b2b0 sp=0xc78cf1b240 pc=0x521f1f github.com/google/zoekt/web.(Server).formatResults(0xc8c30f4000, 0xcab91ee120, 0xcab8a6f228, 0x8, 0xcab898b200, 0xc /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/snippets.go:100 +0xa04 fp=0xc78cf1ba70 sp=0 github.com/google/zoekt/web.(Server).serveSearchErr(0xc8c30f4000, 0x98a2c0, 0xca94640a80, 0xc8289af800, 0x0, 0x0) /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/server.go:244 +0x48e fp=0xc78cf1bc68 sp=0xc github.com/google/zoekt/web.(Server).serveSearch(0xc8c30f4000, 0x98a2c0, 0xca94640a80, 0xc8289af800) /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/server.go:157 +0x4d fp=0xc78cf1bcc0 sp=0xc7 github.com/google/zoekt/web.(Server).(github.com/google/zoekt/web.serveSearch)-fm(0x98a2c0, 0xca94640a80, 0xc8289af /usr/local/google/home/hanwen/go/src/github.com/google/zoekt/web/server.go:146 +0x48 fp=0xc78cf1bcf0 sp=0xc7 net/http.HandlerFunc.ServeHTTP(0xc8b6c8d0e0, 0x98a2c0, 0xca94640a80, 0xc8289af800) /usr/lib/google-golang/src/net/http/server.go:1946 +0x44 fp=0xc78cf1bd18 sp=0xc78cf1bcf0 pc=0x7c64d4 net/http.(ServeMux).ServeHTTP(0xc894d09890, 0x98a2c0, 0xca94640a80, 0xc8289af800) /usr/lib/google-golang/src/net/http/server.go:2336 +0x130 fp=0xc78cf1bd58 sp=0xc78cf1bd18 pc=0x7c8140 net/http.serverHandler.ServeHTTP(0xc8c30f6000, 0x98a2c0, 0xca94640a80, 0xc8289af800) /usr/lib/google-golang/src/net/http/server.go:2693 +0xbc fp=0xc78cf1bd88 sp=0xc78cf1bd58 pc=0x7c917c net/http.(conn).serve(0xc8a8914500, 0x98a740, 0xca946915c0) /usr/lib/google-golang/src/net/http/server.go:1829 +0x651 fp=0xc78cf1bfc8 sp=0xc78cf1bd88 pc=0x7c54f1 Ma

[hanwen]

https://github.com/google/zoekt/blob/ce72fc5eefdbb9ab76d38505e374674b0334700c/web/snippets.go#L100

    if dup, ok := seenFiles[string(f.Checksum)]; ok {
        fMatch.DuplicateID = dup

[hanwen]

full-trace.txt

[hanwen]

version was zoekt-2018-03-02T1238-0897ee3/zoekt-webserver

(gdb) p 'runtime.buildVersion' $1 = 0x9365b5 "go1.10"

[hanwen]

probably compiled with

$ dpkg -s google-golang Package: google-golang Status: install ok installed Priority: extra Section: misc Maintainer: gophers@google.com Architecture: amd64 Version: 1.186670733 Description: Go compiler toolchain (Google) Installs the Go compiler and other auxiliary tools such as gofmt and godoc.

[hanwen]

source code doesn't use unsafe (anymore).

[hanwen]

CheckSum is mmapped directly from the index shard. This data is probably not accessed under lock, so an munmap for reload of shard data will cause trouble.

[hanwen]

Idea for test:

• search for thing
• overwrite the underlying index data
• check that no result has suspect bytes.