From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Brauner Subject: Re: [PATCH 03/11] security: commoncap: fix -Wstringop-overread warning Date: Mon, 22 Mar 2021 17:31:31 +0100 Message-ID: <20210322163131.yaovowes2raydgyg@wittgenstein> References: <20210322160253.4032422-1-arnd@kernel.org> <20210322160253.4032422-4-arnd@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20210322160253.4032422-4-arnd-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> List-ID: Content-Type: text/plain; charset="utf-8" To: Arnd Bergmann Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Martin Sebor , Serge Hallyn , James Morris , Arnd Bergmann , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Ning Sun , Jani Nikula , Kalle Valo , Simon Kelley , James Smart , "James E.J. Bottomley" , Anders Larsen , Tejun Heo , Imre Deak , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, tboot-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, intel-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, ath11k-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups@vger On Mon, Mar 22, 2021 at 05:02:41PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > gcc-11 introdces a harmless warning for cap_inode_getsecurity: > > security/commoncap.c: In function ‘cap_inode_getsecurity’: > security/commoncap.c:440:33: error: ‘memcpy’ reading 16 bytes from a region of size 0 [-Werror=stringop-overread] > 440 | memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > The problem here is that tmpbuf is initialized to NULL, so gcc assumes > it is not accessible unless it gets set by vfs_getxattr_alloc(). This is > a legitimate warning as far as I can tell, but the code is correct since > it correctly handles the error when that function fails. > > Add a separate NULL check to tell gcc about it as well. > > Signed-off-by: Arnd Bergmann > --- Seems reasonable, Acked-by: Christian Brauner