From: Keith Randall <khr@golang.org>
Date: Fri, 20 Mar 2020 19:25:57 +0000 (-0700)
Subject: [release-branch.go1.14] runtime: handle empty stack in expandFinalInlineFrame
X-Git-Tag: go1.14.2~6
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8980ff45cf766f8ab4a3d28ad758f2930de05b6e;p=gostls13.git

[release-branch.go1.14] runtime: handle empty stack in expandFinalInlineFrame

Fixes #37970

Change-Id: I6fc22bdd65f0263d5672731b73d09249201ab0aa
Reviewed-on: https://go-review.googlesource.com/c/go/+/224458
Reviewed-by: Michael Pratt <mpratt@google.com>
(cherry picked from commit 5bc75a3097a3671055f0f9c503850edbe830601d)
Reviewed-on: https://go-review.googlesource.com/c/go/+/224597
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---

diff --git a/src/runtime/pprof/proto_test.go b/src/runtime/pprof/proto_test.go
index f3456ffede..37e68b9c53 100644
--- a/src/runtime/pprof/proto_test.go
+++ b/src/runtime/pprof/proto_test.go
@@ -422,3 +422,16 @@ func TestFakeMapping(t *testing.T) {
 		}
 	}
 }
+
+// Make sure the profiler can handle an empty stack trace.
+// See issue 37967.
+func TestEmptyStack(t *testing.T) {
+	b := []uint64{
+		3, 0, 500, // hz = 500
+		3, 0, 10, // 10 samples with an empty stack trace
+	}
+	_, err := translateCPUProfile(b)
+	if err != nil {
+		t.Fatalf("translating profile: %v", err)
+	}
+}
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index 997cfa3f7a..b2147c4cb4 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -153,6 +153,9 @@ func (ci *Frames) Next() (frame Frame, more bool) {
 //
 //go:linkname runtime_expandFinalInlineFrame runtime/pprof.runtime_expandFinalInlineFrame
 func runtime_expandFinalInlineFrame(stk []uintptr) []uintptr {
+	if len(stk) == 0 {
+		return stk
+	}
 	pc := stk[len(stk)-1]
 	tracepc := pc - 1