[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <ZN6Xrsssr4Pys8YQ@slm.duckdns.org>
Date: Thu, 17 Aug 2023 11:57:02 -1000
From: Tejun Heo <tj@...nel.org>
To: "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: 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 v3][next] cgroup: Avoid -Wstringop-overflow warnings
On Thu, Aug 17, 2023 at 11:19:13AM -0600, Gustavo A. R. Silva wrote:
> Change the notation from pointer-to-array to pointer-to-pointer.
> With this, we avoid the compiler complaining about trying
> to access a region of size zero as an argument during function
> calls.
>
> This is a workaround to prevent the compiler complaining about
> accessing an array of size zero when evaluating the arguments
> of a couple of function calls. See below:
>
> kernel/cgroup/cgroup.c: In function 'find_css_set':
> kernel/cgroup/cgroup.c:1206:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
> 1206 | cset = find_existing_css_set(old_cset, cgrp, template);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> kernel/cgroup/cgroup.c:1206:16: note: referencing argument 3 of type 'struct cgroup_subsys_state *[0]'
> kernel/cgroup/cgroup.c:1071:24: note: in a call to function 'find_existing_css_set'
> 1071 | static struct css_set *find_existing_css_set(struct css_set *old_cset,
> | ^~~~~~~~~~~~~~~~~~~~~
>
> With the change to pointer-to-pointer, the functions are not prevented
> from being executed, and they will do what they have to do when
> CGROUP_SUBSYS_COUNT == 0.
>
> 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=]
>
> This results in no differences in binary output.
>
> Link: https://github.com/KSPP/linux/issues/316
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Applied to cgroup/for-6.6.
Thanks.
--
tejun
Powered by blists - more mailing lists