From 4c8e8fc301c798c7150d41e96213a17534092ca0 Mon Sep 17 00:00:00 2001
From: Dhananjay Nakrani <dhananjaynakrani@gmail.com>
Date: Sat, 7 Jan 2017 23:42:23 -0800
Subject: [PATCH] cmd/compile: fix segfault in race instrumentation

Fixes #13265.

Change-Id: I792eb4ee26bef8a56e279e23f9802cb39019e0d0
Reviewed-on: https://go-review.googlesource.com/34929
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---
 src/cmd/compile/internal/gc/walk.go |  3 +++
 test/fixedbugs/issue13265.go        | 15 +++++++++++++++
 2 files changed, 18 insertions(+)
 create mode 100644 test/fixedbugs/issue13265.go

diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index e973de968f..a597114252 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -2187,6 +2187,9 @@ func callnew(t *types.Type) *Node {
 }
 
 func iscallret(n *Node) bool {
+	if n == nil {
+		return false
+	}
 	n = outervalue(n)
 	return n.Op == OINDREGSP
 }
diff --git a/test/fixedbugs/issue13265.go b/test/fixedbugs/issue13265.go
new file mode 100644
index 0000000000..3036ba7c24
--- /dev/null
+++ b/test/fixedbugs/issue13265.go
@@ -0,0 +1,15 @@
+// errorcheck -0 -race
+
+// Copyright 2017 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.
+
+// Issue 13265: nil pointer deref.
+
+package p
+
+func f() {
+    var c chan chan chan int
+    for ; ; <-<-<-c {
+    }
+}