From: Tejun Heo <tj@kernel.org>
To: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Josef Bacik <josef@toxicpanda.com>, Jens Axboe <axboe@kernel.dk>,
Shaohua Li <shli@fb.com>,
linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
cgroups@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: [PATCH] blk-throttle: Fix some potential string truncation in tg_prfill_limit()
Date: Fri, 22 Dec 2023 06:42:40 +0900 [thread overview]
Message-ID: <ZYSxUPan9qPNE5Bk@mtj.duckdns.org> (raw)
In-Reply-To: <0461f1d69c84cf5a98ae57012856dace757d319e.1702731206.git.christophe.jaillet@wanadoo.fr>
On Sat, Dec 16, 2023 at 01:54:56PM +0100, Christophe JAILLET wrote:
> When compiled with W=1, we get:
> block/blk-throttle.c: In function ‘tg_prfill_limit’:
> block/blk-throttle.c:1539:74: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=]
> 1539 | snprintf(idle_time, sizeof(idle_time), " idle=%lu",
> | ^
> block/blk-throttle.c:1539:25: note: ‘snprintf’ output between 8 and 27 bytes into a destination of size 26
> 1539 | snprintf(idle_time, sizeof(idle_time), " idle=%lu",
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1540 | tg->idletime_threshold_conf);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> block/blk-throttle.c:1546:43: error: ‘%lu’ directive output may be truncated writing between 1 and 20 bytes into a region of size 17 [-Werror=format-truncation=]
> 1546 | " latency=%lu", tg->latency_target_conf);
> | ^~~
> block/blk-throttle.c:1546:33: note: directive argument in the range [0, 18446744073709551614]
> 1546 | " latency=%lu", tg->latency_target_conf);
> | ^~~~~~~~~~~~~~
> block/blk-throttle.c:1545:25: note: ‘snprintf’ output between 11 and 30 bytes into a destination of size 26
> 1545 | snprintf(latency_time, sizeof(latency_time),
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1546 | " latency=%lu", tg->latency_target_conf);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> In order to fix it, remove all the intermediate buffers and write directly
> into the 'sf' seq_file.
>
> Fixes: ada75b6e5b2a ("blk-throttle: add interface to configure idle time threshold")
> Fixes: ec80991d6fc2 ("blk-throttle: add interface for per-cgroup target latency")
I'm not sure Fixes tags are necessary here given that this isn't something
we'd hit in practice.
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Looks fine to me, so:
Acked-by: Tejun Heo <tj@kernel.org>
But, can you please briefly explain how you tested the patch?
Thanks.
--
tejun
prev parent reply other threads:[~2023-12-21 21:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-16 12:54 [PATCH] blk-throttle: Fix some potential string truncation in tg_prfill_limit() Christophe JAILLET
2023-12-21 21:42 ` Tejun Heo [this message]
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