runtime: fail silently if we unwind over sigpanic into C code
If we're running C code and the code panics, the runtime will inject a
call to sigpanic into the C code just like it would into Go code.
However, the return PC from this sigpanic will be in C code. We used
to silently abort the traceback if we didn't recognize a return PC, so
this went by quietly. Now we're much louder because in general this is
a bad thing. However, in this one particular case, it's fine, so if
we're in cgo and are looking at the return PC of sigpanic, silence the
debug output.
Fixes #23576.
Change-Id: I03d0c14d4e4d25b29b1f5804f5e9ccc4f742f876
Reviewed-on: https://go-review.googlesource.com/90896
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index 8993a75..3b9fedc 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -481,3 +481,24 @@
t.Errorf("expected %q got %v", want, got)
}
}
+
+func TestCgoTracebackSigpanic(t *testing.T) {
+ // Test unwinding over a sigpanic in C code without a C
+ // symbolizer. See issue #23576.
+ if runtime.GOOS == "windows" {
+ // On Windows if we get an exception in C code, we let
+ // the Windows exception handler unwind it, rather
+ // than injecting a sigpanic.
+ t.Skip("no sigpanic in C on windows")
+ }
+ t.Parallel()
+ got := runTestProg(t, "testprogcgo", "TracebackSigpanic")
+ want := "runtime.sigpanic"
+ if !strings.Contains(got, want) {
+ t.Fatalf("want failure containing %q. output:\n%s\n", want, got)
+ }
+ nowant := "unexpected return pc"
+ if strings.Contains(got, nowant) {
+ t.Fatalf("failure incorrectly contains %q. output:\n%s\n", nowant, got)
+ }
+}
diff --git a/src/runtime/testdata/testprogcgo/sigpanic.go b/src/runtime/testdata/testprogcgo/sigpanic.go
new file mode 100644
index 0000000..cb46030
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/sigpanic.go
@@ -0,0 +1,28 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// This program will crash.
+// We want to test unwinding from sigpanic into C code (without a C symbolizer).
+
+/*
+#cgo CFLAGS: -O0
+
+char *pnil;
+
+static int f1(void) {
+ *pnil = 0;
+ return 0;
+}
+*/
+import "C"
+
+func init() {
+ register("TracebackSigpanic", TracebackSigpanic)
+}
+
+func TracebackSigpanic() {
+ C.f1()
+}
diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go
index 0d5b06a..2261942 100644
--- a/src/runtime/traceback.go
+++ b/src/runtime/traceback.go
@@ -286,7 +286,15 @@
// In that context it is okay to stop early.
// But if callback is set, we're doing a garbage collection and must
// get everything, so crash loudly.
- if callback != nil || printing {
+ doPrint := printing
+ if doPrint && gp.m.incgo && f.entry == sigpanicPC {
+ // We can inject sigpanic
+ // calls directly into C code,
+ // in which case we'll see a C
+ // return PC. Don't complain.
+ doPrint = false
+ }
+ if callback != nil || doPrint {
print("runtime: unexpected return pc for ", funcname(f), " called from ", hex(frame.lr), "\n")
tracebackHexdump(gp.stack, &frame, lrPtr)
}
