From 8151dca1824e2b42ddf81e2459a661d9161454a7 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Tue, 20 Oct 2009 08:03:43 -0700
Subject: bug162, over and over

R=ken
OCL=35919
CL=35919
---
 test/nilptr/arrayindex.go | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 test/nilptr/arrayindex.go

(limited to 'test/nilptr/arrayindex.go')

diff --git a/test/nilptr/arrayindex.go b/test/nilptr/arrayindex.go
new file mode 100644
index 000000000..0bc6bf4a8
--- /dev/null
+++ b/test/nilptr/arrayindex.go
@@ -0,0 +1,25 @@
+// $G $D/$F.go && $L $F.$A && (! ./$A.out || echo BUG: should fail)
+
+// Copyright 2009 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
+
+import "unsafe"
+
+var x byte
+
+func main() {
+	var p *[1<<30]byte = nil;
+	x = 123;
+
+	// The problem here is not the use of unsafe:
+	// it is that indexing into p[] with a large
+	// enough index jumps out of the unmapped section
+	// at the beginning of memory and into valid memory.
+	// Pointer offsets and array indices, if they are
+	// very large, need to dereference the base pointer
+	// to trigger a trap.
+	println(p[uintptr(unsafe.Pointer(&x))]);	// should crash
+}
-- 
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