From: Rémy Oudompheng <oudomphe@phare.normalesup.org>
Date: Sat, 6 Oct 2012 10:05:52 +0000 (+0200)
Subject: runtime: fix a panic when growing zero-width-element slices.
X-Git-Tag: go1.1rc2~2242
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=782464aea540e9ebf720509ce627d192d84d92a7;p=gostls13.git

runtime: fix a panic when growing zero-width-element slices.

Fixes #4197.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6611056
---

diff --git a/src/pkg/runtime/slice.c b/src/pkg/runtime/slice.c
index d2cc1684ee..b977f45824 100644
--- a/src/pkg/runtime/slice.c
+++ b/src/pkg/runtime/slice.c
@@ -114,7 +114,7 @@ runtime·growslice(SliceType *t, Slice old, int64 n, Slice ret)
 
 	cap = old.cap + n;
 
-	if((intgo)cap != cap || cap < old.cap || cap > MaxMem / t->elem->size)
+	if((intgo)cap != cap || cap < old.cap || (t->elem->size > 0 && cap > MaxMem/t->elem->size))
 		runtime·panicstring("growslice: cap out of range");
 
 	growslice1(t, old, cap, &ret);
diff --git a/test/fixedbugs/bug457.go b/test/fixedbugs/bug457.go
new file mode 100644
index 0000000000..ee7048972a
--- /dev/null
+++ b/test/fixedbugs/bug457.go
@@ -0,0 +1,15 @@
+// run
+
+// Copyright 2012 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 4197: growing a slice of zero-width elements
+// panics on a division by zero.
+
+package main
+
+func main() {
+	var x []struct{}
+	x = append(x, struct{}{})
+}