linux-kernel - Re: [PATCH][next] cgroup: Avoid -Wstringop-overflow warnings

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Message-ID: <202306201250.6FA10ADF4@keescook>
Date:   Tue, 20 Jun 2023 12:51:04 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH][next] cgroup: Avoid -Wstringop-overflow warnings

On Wed, Jun 14, 2023 at 07:18:22PM -0600, Gustavo A. R. Silva wrote:
> Address the following -Wstringop-overflow warnings seen when
> built with ARM architecture and aspeed_g4_defconfig configuration
> (notice that under this configuration CGROUP_SUBSYS_COUNT == 0):
> kernel/cgroup/cgroup.c:1208:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
> kernel/cgroup/cgroup.c:1258:15: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
> kernel/cgroup/cgroup.c:6089:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
> kernel/cgroup/cgroup.c:6153:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
> 
> These changes are based on commit d20d30ebb199 ("cgroup: Avoid compiler
> warnings with no subsystems").
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Ah nice, this should reduce code size for the "0" case too.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook