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| author | Cherry Zhang <cherryyz@google.com> | 2019-11-13 21:01:01 -0500 |
|---|---|---|
| committer | Cherry Zhang <cherryyz@google.com> | 2019-11-15 02:31:52 +0000 |
| commit | 03c58c9dccde0b9d98962f34e6669a508c8d133a (patch) | |
| tree | 8738d71ba2bc11ce86005e70bff33b66d30fb023 /src/runtime/signal_unix.go | |
| parent | 7719016ee297dd4960bb66ed265038f2d75b3c56 (diff) | |
| download | go-03c58c9dccde0b9d98962f34e6669a508c8d133a.tar.gz go-03c58c9dccde0b9d98962f34e6669a508c8d133a.zip | |
runtime: crash if a signal is received with bad G and no extra M
When we receive a signal, if G is nil we call badsignal, which
calls needm. When cgo is not used, there is no extra M, so needm
will just hang. In this situation, even GOTRACEBACK=crash cannot
get a stack trace, as we're in the signal handler and cannot
receive another signal (SIGQUIT).
Instead, just crash.
For #35554.
Updates #34391.
Change-Id: I061ac43fc0ac480435c050083096d126b149d21f
Reviewed-on: https://go-review.googlesource.com/c/go/+/206959
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Diffstat (limited to 'src/runtime/signal_unix.go')
| -rw-r--r-- | src/runtime/signal_unix.go | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go index 35e641286b..f42de36acc 100644 --- a/src/runtime/signal_unix.go +++ b/src/runtime/signal_unix.go @@ -861,11 +861,22 @@ func signalDuringFork(sig uint32) { throw("signal received during fork") } +var badginsignalMsg = "fatal: bad g in signal handler\n" + // This runs on a foreign stack, without an m or a g. No stack split. //go:nosplit //go:norace //go:nowritebarrierrec func badsignal(sig uintptr, c *sigctxt) { + if !iscgo && !cgoHasExtraM { + // There is no extra M. needm will not be able to grab + // an M. Instead of hanging, just crash. + // Cannot call split-stack function as there is no G. + s := stringStructOf(&badginsignalMsg) + write(2, s.str, int32(s.len)) + exit(2) + *(*uintptr)(unsafe.Pointer(uintptr(123))) = 2 + } needm(0) if !sigsend(uint32(sig)) { // A foreign thread received the signal sig, and the |