[asan] Don't crash on fclose(NULL)

It's explicitly forbidden to call fclose with NULL, but at least on Darwin, this succeeds and doesn't segfault. To maintain binary compatibility, ASan should survice fclose(NULL) as well.

Differential Revision: https://reviews.llvm.org/D40053

llvm-svn: 319347

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

@@ -273,7 +273,7 @@ UNUSED static const FileMetadata *GetInterceptorMetadata(
   MetadataHashMap::Handle h(interceptor_metadata_map, (uptr)addr,
                             /* remove */ false,
                             /* create */ false);
-  if (h.exists()) {
+  if (addr && h.exists()) {
     CHECK(!h.created());
     CHECK(h->type == CommonInterceptorMetadata::CIMT_FILE);
     return &h->file;

compiler-rt/test/asan/TestCases/Darwin/fclose.c

@@ -0,0 +1,13 @@
+// RUN: %clang_asan %s -o %t
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, const char * argv[]) {
+  fclose(NULL);
+  fprintf(stderr, "Finished.\n");
+  return 0;
+}
+
+// CHECK: Finished.