[PATCH] D40052: [asan] Allow getpwnam(NULL) for binary compatibily

[Kuba (Brecka) Mracek via Phabricator via llvm-commits]

kubamracek created this revision.
kubamracek added a project: Sanitizers.

Calling `getpwnam(NULL)` is probably a bug, but at least on Darwin, such a call succeeds without segfaulting. I have some existing code that relies on that. To maintain binary compatibility, ASan should also survive a call to `getpwnam` with `NULL`.


Repository:
  rL LLVM

https://reviews.llvm.org/D40052

Files:
  lib/sanitizer_common/sanitizer_common_interceptors.inc
  test/asan/TestCases/Darwin/getpwnam.c


Index: test/asan/TestCases/Darwin/getpwnam.c
===================================================================
--- test/asan/TestCases/Darwin/getpwnam.c
+++ test/asan/TestCases/Darwin/getpwnam.c
@@ -0,0 +1,15 @@
+// RUN: %clang_asan %s -o %t
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+
+int main(int argc, const char * argv[]) {
+  getpwnam(NULL);
+  fprintf(stderr, "Finished.\n");
+  return 0;
+}
+
+// CHECK: Finished.
Index: lib/sanitizer_common/sanitizer_common_interceptors.inc
===================================================================
--- lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -1724,7 +1724,8 @@
 INTERCEPTOR(__sanitizer_passwd *, getpwnam, const char *name) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, getpwnam, name);
-  COMMON_INTERCEPTOR_READ_RANGE(ctx, name, REAL(strlen)(name) + 1);
+  if (name)
+    COMMON_INTERCEPTOR_READ_RANGE(ctx, name, REAL(strlen)(name) + 1);
   __sanitizer_passwd *res = REAL(getpwnam)(name);
   if (res) unpoison_passwd(ctx, res);
   return res;


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