From: Alejandro Colomar <alx.manpages@gmail.com>
To: Siddhesh Poyarekar <siddhesh@gotplt.org>, GCC <gcc@gcc.gnu.org>
Cc: "Iker Pedrosa" <ipedrosa@redhat.com>,
"David Malcolm" <dmalcolm@redhat.com>,
"Florian Weimer" <fweimer@redhat.com>,
"Sam James" <sam@gentoo.org>, "Paul Eggert" <eggert@cs.ucla.edu>,
"Michael Kerrisk" <mtk.manpages@gmail.com>,
"Martin Uecker" <uecker@tugraz.at>,
"Jₑₙₛ Gustedt" <jens.gustedt@inria.fr>,
"Yann Droneaud" <ydroneaud@opteya.com>
Subject: Re: Missed warning (-Wuse-after-free)
Date: Fri, 17 Feb 2023 12:22:53 +0100 [thread overview]
Message-ID: <f54ba6cb-0edb-5637-6936-4855506c7eb2@gmail.com> (raw)
In-Reply-To: <d2b243e9-a9a9-bc58-5364-4cca938a9590@gotplt.org>
[-- Attachment #1.1: Type: text/plain, Size: 1486 bytes --]
Hi Siddhesh,
On 2/17/23 04:48, Siddhesh Poyarekar wrote:
> On 2023-02-16 10:15, David Malcolm via Gcc wrote:
>> I'm not convinced that it's useful to the end-user to warn about the
>> "use of q itself" case.
>
> FWIW, -Wuse-after-free=3 already should do this:
Thanks! It works. I would have expected such a warning to be included
in -Wextra. Does it have any false positives (or maybe too many false
negatives?) that make it unsuitable for -Wextra?
>
> At level 3, the warning also diagnoses uses of indeterminate pointers in
> equality expressions. All uses of indeterminate pointers are undefined
> but equality tests sometimes appear after
> calls to "realloc" as an attempt to determine whether the call resulted
> in relocating the object to a different address. They are diagnosed at
> a separate level to aid legacy code gradually
> transition to safe alternatives. For example, the equality test in the
> function below is diagnosed at this level:
>
> Jakub and I had discussed this in the context of _FORTIFY_SOURCE=3
> (which is anal about this and can break things) and we got pr#105217,
> but that is also a best-effort thing, not really a guarantee.
>
> IMO the analyzer should go that extra mile and warn for the use of q
> itself and maybe deprecate -Wuse-after-free=3 in its favour.
>
> Sid
Cheers,
Alex
--
<http://www.alejandro-colomar.es/>
GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2023-02-17 11:23 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-16 14:35 Alejandro Colomar
2023-02-16 15:15 ` David Malcolm
2023-02-17 1:04 ` Alejandro Colomar
2023-02-17 1:05 ` Alejandro Colomar
2023-02-17 1:56 ` Sam James
2023-02-17 8:12 ` Martin Uecker
2023-02-17 11:35 ` Alejandro Colomar
2023-02-17 13:34 ` Andreas Schwab
2023-02-17 13:48 ` Martin Uecker
2023-02-23 19:23 ` Alex Colomar
2023-02-23 19:57 ` Martin Uecker
2023-02-24 0:02 ` Alex Colomar
2023-02-24 1:21 ` Serge E. Hallyn
2023-02-24 1:42 ` Alex Colomar
2023-02-24 3:01 ` Peter Lafreniere
2023-02-24 8:52 ` Martin Uecker
2023-02-24 8:43 ` Martin Uecker
2023-02-24 16:10 ` Serge E. Hallyn
2023-02-24 8:36 ` Martin Uecker
2023-02-24 16:01 ` Serge E. Hallyn
2023-02-24 16:37 ` Martin Uecker
2023-02-17 3:48 ` Siddhesh Poyarekar
2023-02-17 11:22 ` Alejandro Colomar [this message]
2023-02-17 13:38 ` Siddhesh Poyarekar
2023-02-17 14:01 ` Mark Wielaard
2023-02-17 14:06 ` Siddhesh Poyarekar
2023-02-17 21:20 ` [PATCH] Make -Wuse-after-free=3 the default one in -Wall Alejandro Colomar
2023-02-17 21:39 ` Siddhesh Poyarekar
2023-02-17 21:41 ` Siddhesh Poyarekar
2023-02-17 22:58 ` Alejandro Colomar
2023-02-17 23:03 ` Siddhesh Poyarekar
2023-02-17 11:24 ` Missed warning (-Wuse-after-free) Jonathan Wakely
2023-02-17 11:43 ` Alejandro Colomar
2023-02-17 12:04 ` Jonathan Wakely
2023-02-17 12:53 ` Siddhesh Poyarekar
2023-02-17 14:10 ` Jonathan Wakely
2023-02-17 13:44 ` David Malcolm
2023-02-17 14:01 ` Siddhesh Poyarekar
2023-02-17 8:49 ` Yann Droneaud
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f54ba6cb-0edb-5637-6936-4855506c7eb2@gmail.com \
--to=alx.manpages@gmail.com \
--cc=dmalcolm@redhat.com \
--cc=eggert@cs.ucla.edu \
--cc=fweimer@redhat.com \
--cc=gcc@gcc.gnu.org \
--cc=ipedrosa@redhat.com \
--cc=jens.gustedt@inria.fr \
--cc=mtk.manpages@gmail.com \
--cc=sam@gentoo.org \
--cc=siddhesh@gotplt.org \
--cc=uecker@tugraz.at \
--cc=ydroneaud@opteya.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).