1 files changed, 72 insertions, 0 deletions
diff --git a/misc/cgo/testsanitizers/testdata/msan6.go b/misc/cgo/testsanitizers/testdata/msan6.go
new file mode 100644
index 0000000..003989c
--- /dev/null
+++ b/misc/cgo/testsanitizers/testdata/msan6.go
@@ -0,0 +1,72 @@
+// Copyright 2018 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
+
+// A C function returning a value on the Go stack could leave the Go
+// stack marked as uninitialized, potentially causing a later error
+// when the stack is used for something else. Issue 26209.
+
+/*
+#cgo LDFLAGS: -fsanitize=memory
+#cgo CPPFLAGS: -fsanitize=memory
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+	uintptr_t a[20];
+} S;
+
+S f() {
+	S *p;
+
+	p = (S *)(malloc(sizeof(S)));
+	p->a[0] = 0;
+	return *p;
+}
+*/
+import "C"
+
+// allocateStack extends the stack so that stack copying doesn't
+// confuse the msan data structures.
+//go:noinline
+func allocateStack(i int) int {
+	if i == 0 {
+		return i
+	}
+	return allocateStack(i - 1)
+}
+
+// F1 marks a chunk of stack as uninitialized.
+// C.f returns an uninitialized struct on the stack, so msan will mark
+// the stack as uninitialized.
+//go:noinline
+func F1() uintptr {
+	s := C.f()
+	return uintptr(s.a[0])
+}
+
+// F2 allocates a struct on the stack and converts it to an empty interface,
+// which will call msanread and see that the data appears uninitialized.
+//go:noinline
+func F2() interface{} {
+	return C.S{}
+}
+
+func poisonStack(i int) int {
+	if i == 0 {
+		return int(F1())
+	}
+	F1()
+	r := poisonStack(i - 1)
+	F2()
+	return r
+}
+
+func main() {
+	allocateStack(16384)
+	poisonStack(128)
+}