[sanitizer] Fix PR17138.

strerror_r on OSX returns a positive error code when the errno value is
unknown. Buffer contents are initialized in any case.

llvm-svn: 190295

2 files changed, 17 insertions, 2 deletions

diff --git a/compiler-rt/lib/asan/lit_tests/TestCases/strerror_r_test.cc b/compiler-rt/lib/asan/lit_tests/TestCases/strerror_r_test.cc
new file mode 100644
index 00000000000..0df009b83f9
--- /dev/null
+++ b/compiler-rt/lib/asan/lit_tests/TestCases/strerror_r_test.cc
@@ -0,0 +1,13 @@
+// RUN: %clangxx_asan -O0 %s -o %t && %t
+
+// Regression test for PR17138.
+
+#include <assert.h>
+#include <string.h>
+
+int main() {
+  char buf[1024];
+  char *res = (char *)strerror_r(300, buf, sizeof(buf));
+  assert(res != 0);
+  return 0;
+}
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
index 49982584edc..0322f2bd531 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -1807,12 +1807,14 @@ INTERCEPTOR(char *, strerror_r, int errnum, char *buf, SIZE_T buflen) {
   //    writes message to buf.
   //  * GNU version returns message pointer, which points to either buf or some
   //    static storage.
-  if (!res) {
+  SIZE_T posix_res = (SIZE_T)res;
+  if (posix_res < 1024 || posix_res > (SIZE_T) - 1024) {
     // POSIX version. Spec is not clear on whether buf is NULL-terminated.
+    // At least on OSX, buf contents are valid even when the call fails.
     SIZE_T sz = internal_strnlen(buf, buflen);
     if (sz < buflen) ++sz;
     COMMON_INTERCEPTOR_WRITE_RANGE(ctx, buf, sz);
-  } else if ((SIZE_T)res < (SIZE_T) - 1024) {
+  } else {
     // GNU version.
     COMMON_INTERCEPTOR_WRITE_RANGE(ctx, res, REAL(strlen)(res) + 1);
   }