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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/104069] -Werror=use-after-free false positive on elfutils-0.186
Date: Wed, 19 Jan 2022 20:34:29 +0000 [thread overview]
Message-ID: <bug-104069-4-8kMMJB4cZu@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-104069-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104069
--- Comment #18 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Martin Sebor from comment #14)
> Removing the test for !size from the first conditional avoids the warning.
> I don't fully understand what the code tries to do but the following avoids
> it at -O2 (only):
>
> void *xrealloc (void *ptr, int size)
> {
> if (!size)
> size = 1;
> void *ret = __builtin_realloc (ptr, size);
> if (!ret)
> ret = __builtin_realloc (ptr, 1);
> if (!ret) {
> ret = __builtin_realloc (ptr, size);
> if (!ret)
> ret = __builtin_realloc(ptr, 1);
> if (!ret)
> __builtin_abort ();
> }
> return ret;
> }
This is definitely not what the code meant to do.
If I do xrealloc (malloc (30), 1024 * 1024 * 1024) and it returns non-NULL,
it certainly shouldn't be that it under the hood called realloc (ptr, 1)
because
the first realloc failed.
If you add that if (!size) size = 1;, then I think what is meant is just
void *ret = __builtin_realloc (ptr, size);
if (!ret)
{
ret = __builtin_realloc (ptr, size);
if (!ret)
die (...);
}
return ret;
next prev parent reply other threads:[~2022-01-19 20:34 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-17 17:18 [Bug c/104069] New: " slyfox at gcc dot gnu.org
2022-01-17 17:27 ` [Bug tree-optimization/104069] " pinskia at gcc dot gnu.org
2022-01-17 17:29 ` slyfox at gcc dot gnu.org
2022-01-17 19:10 ` msebor at gcc dot gnu.org
2022-01-17 21:52 ` msebor at gcc dot gnu.org
2022-01-18 9:37 ` slyfox at gcc dot gnu.org
2022-01-18 22:03 ` msebor at gcc dot gnu.org
2022-01-18 22:06 ` [Bug middle-end/104069] " msebor at gcc dot gnu.org
2022-01-18 22:17 ` jakub at gcc dot gnu.org
2022-01-18 22:47 ` msebor at gcc dot gnu.org
2022-01-18 22:56 ` jakub at gcc dot gnu.org
2022-01-19 0:51 ` amacleod at redhat dot com
2022-01-19 1:04 ` cvs-commit at gcc dot gnu.org
2022-01-19 20:22 ` msebor at gcc dot gnu.org
2022-01-19 20:24 ` msebor at gcc dot gnu.org
2022-01-19 20:30 ` pinskia at gcc dot gnu.org
2022-01-19 20:31 ` pinskia at gcc dot gnu.org
2022-01-19 20:32 ` msebor at gcc dot gnu.org
2022-01-19 20:34 ` jakub at gcc dot gnu.org [this message]
2022-01-19 20:42 ` jakub at gcc dot gnu.org
2022-01-19 20:54 ` msebor at gcc dot gnu.org
2022-01-31 11:18 ` jakub at gcc dot gnu.org
2022-03-17 19:32 ` msebor at gcc dot gnu.org
2022-05-16 14:14 ` eike@sf-mail.de
2022-08-24 8:51 ` vincent at systemli dot org
2022-10-27 16:57 ` mark at gcc dot gnu.org
2022-10-28 7:36 ` slyfox at gcc dot gnu.org
2023-05-10 3:35 ` [Bug middle-end/104069] Wuse-after-free=2 -O0 false positive "may be used" mkaracsony81 at gmail dot com
2023-05-12 7:00 ` slyfox at gcc dot gnu.org
2023-05-12 8:30 ` mkaracsony81 at gmail dot com
2023-05-12 9:08 ` slyfox at gcc dot gnu.org
2023-05-12 13:20 ` mkaracsony81 at gmail dot com
2023-05-12 20:36 ` slyfox at gcc dot gnu.org
2023-05-13 5:07 ` mkaracsony81 at gmail dot com
2023-05-13 5:07 ` mkaracsony81 at gmail dot com
2023-12-17 4:40 ` lavr at ncbi dot nlm.nih.gov
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