1 files changed, 35 insertions, 0 deletions
diff --git a/test/nilptr/structfield2.go b/test/nilptr/structfield2.go
new file mode 100644
index 000000000..f11e3df67
--- /dev/null
+++ b/test/nilptr/structfield2.go
@@ -0,0 +1,35 @@
+// $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 dummy [512<<20]byte;	// give us a big address space
+type T struct {
+	x [256<<20] byte;
+	i int;
+}
+
+var y *T;
+var x = &y;
+
+func main() {
+	// the test only tests what we intend to test
+	// if dummy starts in the first 256 MB of memory.
+	// otherwise there might not be anything mapped
+	// at the address that might be accidentally
+	// dereferenced below.
+	if uintptr(unsafe.Pointer(&dummy)) > 256<<20 {
+		panic("dummy too far out");
+	}
+
+	// The problem here is that indexing into t with a large
+	// enough index can jump out of the unmapped section
+	// at the beginning of memory and into valid memory.
+	// We require the pointer dereference to check.
+	println((*x).i);	// should crash
+}