commit 6484ae5b8c4d4314f748e4d3c9a9baa5385e57c5

Author: Carlos O'Donell <carlos@redhat.com>

Date:   Fri Jan 28 15:14:29 2022 -0500

    malloc: Fix -Wuse-after-free warning in tst-mallocalign1 [BZ #26779]

    The test leaks bits from the freed pointer via the return value

    in ret, and the compiler correctly identifies this issue.

    We switch the test to use TEST_VERIFY and terminate the test

    if any of the pointers return an unexpected alignment.

    This fixes another -Wuse-after-free error when compiling glibc

    with gcc 12.

    Tested on x86_64 and i686 without regression.

    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

    (cherry picked from commit 3a7bed5f5a527dbd87412551f41e42e63aeef07a)

diff --git a/malloc/tst-mallocalign1.c b/malloc/tst-mallocalign1.c

index 294e821afebd25ac..3e09ff30c4aa9f91 100644

--- a/malloc/tst-mallocalign1.c

+++ b/malloc/tst-mallocalign1.c

@@ -20,6 +20,7 @@

 #include <stdlib.h>

 #include <inttypes.h>

 #include <malloc-size.h>

+#include <support/check.h>

 static void *

 test (size_t s)

@@ -31,41 +32,42 @@ test (size_t s)

   return p;

 }

+#define ALIGNED(p) (((uintptr_t )p & MALLOC_ALIGN_MASK) == 0)

+

 static int

 do_test (void)

 {

   void *p;

-  int ret = 0;

   p = test (2);

-  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;

+  TEST_VERIFY (ALIGNED (p));

   free (p);

   p = test (8);

-  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;

+  TEST_VERIFY (ALIGNED (p));

   free (p);

   p = test (13);

-  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;

+  TEST_VERIFY (ALIGNED (p));

   free (p);

   p = test (16);

-  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;

+  TEST_VERIFY (ALIGNED (p));

   free (p);

   p = test (23);

-  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;

+  TEST_VERIFY (ALIGNED (p));

   free (p);

   p = test (43);

-  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;

+  TEST_VERIFY (ALIGNED (p));

   free (p);

   p = test (123);

-  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;

+  TEST_VERIFY (ALIGNED (p));

   free (p);

-  return ret;

+  return 0;

 }

 #include <support/test-driver.c>