From: Carlos O'Donell <carlos@redhat.com>
To: libc-alpha@sourceware.org, joseph@codesourcery.com
Subject: [PATCH] malloc: Fix -Wuse-after-free warning in tst-mallocalign1 [BZ #26779]
Date: Mon, 31 Jan 2022 00:21:32 -0500 [thread overview]
Message-ID: <20220131052132.3854764-1-carlos@redhat.com> (raw)
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.
---
malloc/tst-mallocalign1.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/malloc/tst-mallocalign1.c b/malloc/tst-mallocalign1.c
index 8bfd50c468..3116748e7e 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>
--
2.34.1
next reply other threads:[~2022-01-31 5:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-31 5:21 Carlos O'Donell [this message]
2022-01-31 5:32 ` Siddhesh Poyarekar
2022-01-31 6:00 ` Carlos O'Donell
2022-01-31 8:31 ` Andreas Schwab
2022-01-31 15:20 ` Carlos O'Donell
2022-02-01 17:08 ` Carlos O'Donell
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