[asan] Fix handling of %m in printf interceptor.

llvm-svn: 290632

1 files changed, 14 insertions, 0 deletions

diff --git a/compiler-rt/test/asan/TestCases/printf-m.c b/compiler-rt/test/asan/TestCases/printf-m.c
new file mode 100644
index 00000000000..1e5ebd92e3e
--- /dev/null
+++ b/compiler-rt/test/asan/TestCases/printf-m.c
@@ -0,0 +1,14 @@
+// RUN: %clang_asan -O2 %s -o %t && %run %t
+
+// FIXME: printf is not intercepted on Windows yet.
+// XFAIL: win32
+
+#include <stdio.h>
+
+int main() {
+  char s[5] = {'w', 'o', 'r', 'l', 'd'};
+  // Test that %m does not consume an argument. If it does, %s would apply to
+  // the 5-character buffer, resulting in a stack-buffer-overflow report.
+  printf("%m %s, %.5s\n", "hello", s);
+  return 0;
+}