From: "Martin Ågren" <martin.agren@gmail.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH] leak tests: free() before die for two API functions
Date: Thu, 21 Oct 2021 18:13:00 +0200 [thread overview]
Message-ID: <CAN0heSqA4uqWahWKTa0ZLBCnFLG4jxEx+18aVQUieX0f6dzWMw@mail.gmail.com> (raw)
In-Reply-To: <patch-1.1-5a47bf2e9c9-20211021T114223Z-avarab@gmail.com>
On Thu, 21 Oct 2021 at 13:43, Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>
> Call free() just before die() in two API functions whose tests are
> asserted under SANITIZE=leak. Normally this would not be needed due to
> how SANITIZE=leak works, but in these cases my GCC version (10.2.1-6)
> will fail tests t0001 and t0017 under SANITIZE=leak depending on the
> optimization level.
Seems a bit unfortunate. I have to wonder why these in particular
trigger this compiler bug or whatever it is, but oh well.
> - if (check_refname_format(full_ref, 0))
> + if (check_refname_format(full_ref, 0)) {
> + free(ret);
> + free(full_ref);
> die(_("invalid branch name: %s = %s"), config_display_key, ret);
> + }
> free(full_ref);
This looks like use-after-free. Rather than complicating this by, e.g.,
first formatting the string, then freeing `ret`, then dying, could we --
if we really want this workaround -- make the workaround be `UNLEAK`
instead?
Also, if we do something like this patch, I think we should try to avoid
this free-before-die then being cargo-culted all across the codebase.
How about
UNLEAK(ret); /* work around compiler bug */
UNLEAK(full_ref); /* work around compiler bug */
or something?
Martin
next prev parent reply other threads:[~2021-10-21 16:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 11:42 [PATCH] leak tests: free() before die for two API functions Ævar Arnfjörð Bjarmason
2021-10-21 15:33 ` Andrzej Hunt
2021-10-21 18:51 ` Junio C Hamano
2021-10-21 16:13 ` Martin Ågren [this message]
2021-10-21 19:54 ` [PATCH v2 0/3] refs.c + config.c: plug memory leaks Ævar Arnfjörð Bjarmason
2021-10-21 19:54 ` [PATCH v2 1/3] refs.c: make "repo_default_branch_name" static, remove xstrfmt() Ævar Arnfjörð Bjarmason
2021-10-21 23:26 ` Junio C Hamano
2021-10-21 19:54 ` [PATCH v2 2/3] config.c: don't leak memory in handle_path_include() Ævar Arnfjörð Bjarmason
2021-10-21 23:30 ` Junio C Hamano
2021-10-22 17:19 ` Ævar Arnfjörð Bjarmason
2021-10-22 21:21 ` Junio C Hamano
2021-10-22 22:30 ` Ævar Arnfjörð Bjarmason
2021-10-21 19:54 ` [PATCH v2 3/3] config.c: free(expanded) before die(), work around GCC oddity Ævar Arnfjörð Bjarmason
2021-10-21 23:32 ` Junio C Hamano
2021-10-22 18:19 ` [PATCH v3 0/6] usage.c: add die_message() & plug memory leaks in refs.c & config.c Ævar Arnfjörð Bjarmason
2021-10-22 18:19 ` [PATCH v3 1/6] usage.c: add a die_message() routine Ævar Arnfjörð Bjarmason
2021-10-24 5:49 ` Junio C Hamano
2021-10-22 18:19 ` [PATCH v3 2/6] usage.c API users: use die_message() where appropriate Ævar Arnfjörð Bjarmason
2021-10-22 18:19 ` [PATCH v3 3/6] usage.c + gc: add and use a die_message_errno() Ævar Arnfjörð Bjarmason
2021-10-24 5:52 ` Junio C Hamano
2021-10-22 18:19 ` [PATCH v3 4/6] config.c: don't leak memory in handle_path_include() Ævar Arnfjörð Bjarmason
2021-10-24 5:53 ` Junio C Hamano
2021-10-22 18:19 ` [PATCH v3 5/6] config.c: free(expanded) before die(), work around GCC oddity Ævar Arnfjörð Bjarmason
2021-10-26 8:53 ` Jeff King
2021-10-22 18:19 ` [PATCH v3 6/6] refs: plug memory leak in repo_default_branch_name() Ævar Arnfjörð Bjarmason
2021-10-27 21:50 ` [PATCH v3 0/6] usage.c: add die_message() & plug memory leaks in refs.c & config.c Jonathan Tan
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