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[2603:800c:1a02:1bae:44e6:6a58:44be:40a6]) by smtp.gmail.com with ESMTPSA id z9sm15038224pfa.2.2021.08.30.11.10.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Aug 2021 11:10:36 -0700 (PDT) Sender: Tejun Heo Date: Mon, 30 Aug 2021 08:10:34 -1000 From: Tejun Heo To: Kees Cook Cc: Stephen Rothwell , Zefan Li , Johannes Weiner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v3] cgroup: Avoid compiler warnings with no subsystems Message-ID: References: <20210828000255.3213497-1-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210828000255.3213497-1-keescook@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 27, 2021 at 05:02:55PM -0700, Kees Cook wrote: > As done before in commit cb4a31675270 ("cgroup: use bitmask to filter > for_each_subsys"), avoid compiler warnings for the pathological case of > having no subsystems (i.e. CGROUP_SUBSYS_COUNT == 0). This condition is > hit for the arm multi_v7_defconfig config under -Wzero-length-bounds: > > In file included from ./arch/arm/include/generated/asm/rwonce.h:1, > from include/linux/compiler.h:264, > from include/uapi/linux/swab.h:6, > from include/linux/swab.h:5, > from arch/arm/include/asm/opcodes.h:86, > from arch/arm/include/asm/bug.h:7, > from include/linux/bug.h:5, > from include/linux/thread_info.h:13, > from include/asm-generic/current.h:5, > from ./arch/arm/include/generated/asm/current.h:1, > from include/linux/sched.h:12, > from include/linux/cgroup.h:12, > from kernel/cgroup/cgroup-internal.h:5, > from kernel/cgroup/cgroup.c:31: > kernel/cgroup/cgroup.c: In function 'of_css': > kernel/cgroup/cgroup.c:651:42: warning: array subscript '' is outside the bounds of an > interior zero-length array 'struct cgroup_subsys_state *[0]' [-Wzero-length-bounds] > 651 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); > > Reported-by: Stephen Rothwell > Cc: Tejun Heo > Cc: Zefan Li > Cc: Johannes Weiner > Cc: cgroups@vger.kernel.org > Signed-off-by: Kees Cook Applied to cgroup/for-5.15. Thanks. -- tejun