From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>,
git@vger.kernel.org,
"Johannes Schindelin" <johannes.schindelin@gmx.de>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: Re: [PATCH 11/11] bug_fl(): add missing `va_end()` call
Date: Wed, 15 Jun 2022 22:00:14 -0700 [thread overview]
Message-ID: <xmqq8rpxw6ch.fsf@gitster.g> (raw)
In-Reply-To: <Yqq3O5hykBecoVKQ@coredump.intra.peff.net> (Jeff King's message of "Thu, 16 Jun 2022 00:53:15 -0400")
Jeff King <peff@peff.net> writes:
> On Wed, Jun 15, 2022 at 11:35:45PM +0000, Johannes Schindelin via GitGitGadget wrote:
>
>> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>>
>> According to the manual:
>>
>> Each invocation of va_copy() must be matched by a corresponding
>> invocation of va_end() in the same function.
>>
>> Note: There is another instance of `va_copy()` in `usage.c` that is
>> missing a `va_end()` call, in `BUG_vfl()`. It does not matter there,
>> though, because that function either `exit()`s or `abort()`s, anyway.
>>
>> Reported by Coverity.
>
> This was introduced by the recent 0cc05b044f (usage.c: add a non-fatal
> bug() function to go with BUG(), 2022-06-02). But there's a much worse
> bug in the same function. The code introduced by that patch does:
>
> va_list ap, cp;
> [...]
> va_copy(cp, ap);
> va_start(ap, fmt);
>
> So "cp" is copied from "ap" before we have actually initialized "ap".
> It's surprising that this works at all. The two lines should be flipped.
Yes, it is surprising. Perhaps it is not working at all.
Thanks for an extra set of eyeballs.
> IMHO, since we're in the actual varargs function itself, it would be
> simpler to just bracket each use with start/end, rather than copying,
> like:
>
> diff --git a/usage.c b/usage.c
> index 79900d0287..56e29d6cd6 100644
> --- a/usage.c
> +++ b/usage.c
> @@ -334,15 +334,17 @@ NORETURN void BUG_fl(const char *file, int line, const char *fmt, ...)
> int bug_called_must_BUG;
> void bug_fl(const char *file, int line, const char *fmt, ...)
> {
> - va_list ap, cp;
> + va_list ap;
>
> bug_called_must_BUG = 1;
>
> - va_copy(cp, ap);
> va_start(ap, fmt);
> BUG_vfl_common(file, line, fmt, ap);
> va_end(ap);
> - trace2_cmd_error_va(fmt, cp);
> +
> + va_start(ap, fmt);
> + trace2_cmd_error_va(fmt, ap);
> + va_end(ap);
> }
>
> #ifdef SUPPRESS_ANNOTATED_LEAKS
>
> but I am happy with any solution that is correct. :)
>
> -Peff
next prev parent reply other threads:[~2022-06-16 5:00 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-15 23:35 [PATCH 00/11] Coverity fixes Johannes Schindelin via GitGitGadget
2022-06-15 23:35 ` [PATCH 01/11] mingw: avoid accessing uninitialized memory in `is_executable()` Johannes Schindelin via GitGitGadget
2022-06-16 4:07 ` Junio C Hamano
2022-06-16 19:53 ` René Scharfe
2022-06-16 20:13 ` Junio C Hamano
2022-06-16 20:20 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 02/11] fsmonitor: avoid memory leak in `fsm_settings__get_incompatible_msg()` Johannes Schindelin via GitGitGadget
2022-06-16 4:10 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 03/11] submodule--helper: avoid memory leak in `update_submodule()` Johannes Schindelin via GitGitGadget
2022-06-16 4:23 ` Junio C Hamano
2022-06-16 17:51 ` Glen Choo
2022-06-15 23:35 ` [PATCH 04/11] get_oid_with_context_1(): avoid use-after-free Johannes Schindelin via GitGitGadget
2022-06-16 4:29 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 05/11] submodule-config: avoid memory leak Johannes Schindelin via GitGitGadget
2022-06-16 4:36 ` Junio C Hamano
2022-06-16 18:09 ` Glen Choo
2022-06-15 23:35 ` [PATCH 06/11] pack-redundant: avoid using uninitialized memory Johannes Schindelin via GitGitGadget
2022-06-16 4:53 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 07/11] submodule--helper: avoid memory leak when fetching submodules Johannes Schindelin via GitGitGadget
2022-06-16 4:55 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 08/11] read_index_from(): avoid memory leak Johannes Schindelin via GitGitGadget
2022-06-17 21:27 ` Tom Levy
2022-06-15 23:35 ` [PATCH 09/11] pack-mtimes: avoid closing a bogus file descriptor Johannes Schindelin via GitGitGadget
2022-06-16 20:43 ` Taylor Blau
2022-06-15 23:35 ` [PATCH 10/11] relative_url(): fix incorrect condition Johannes Schindelin via GitGitGadget
2022-06-16 5:02 ` Junio C Hamano
2022-06-16 13:09 ` Ævar Arnfjörð Bjarmason
2022-06-16 17:55 ` Junio C Hamano
2022-06-16 16:41 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 11/11] bug_fl(): add missing `va_end()` call Johannes Schindelin via GitGitGadget
2022-06-16 4:53 ` Jeff King
2022-06-16 5:00 ` Junio C Hamano [this message]
2022-06-16 13:02 ` Ævar Arnfjörð Bjarmason
2022-06-16 18:03 ` Junio C Hamano
2022-06-16 19:20 ` Jeff King
2022-06-16 20:04 ` [PATCH] bug_fl(): correctly initialize trace2 va_list Jeff King
2022-06-16 20:11 ` [PATCH 11/11] bug_fl(): add missing `va_end()` call Junio C Hamano
2022-06-16 4:05 ` [PATCH 00/11] Coverity fixes Junio C Hamano
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