Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753074AbbGARhX (ORCPT ); Wed, 1 Jul 2015 13:37:23 -0400 Received: from mail-ob0-f170.google.com ([209.85.214.170]:36529 "EHLO mail-ob0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753211AbbGARhR (ORCPT ); Wed, 1 Jul 2015 13:37:17 -0400 MIME-Version: 1.0 In-Reply-To: <559420DA.3010401@canonical.com> References: <1435769495-2025-1-git-send-email-colin.king@canonical.com> <559420DA.3010401@canonical.com> Date: Wed, 1 Jul 2015 13:37:15 -0400 X-Google-Sender-Auth: XlSUzATuIFBQSS7vvT6nf4qtj-0 Message-ID: Subject: Re: [PATCH] drm/nouveau: usif_ioctl: ensure returns are initialized From: Ilia Mirkin To: Colin Ian King Cc: Emil Velikov , Ben Skeggs , "dri-devel@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2587 Lines: 49 On Wed, Jul 1, 2015 at 1:18 PM, Colin Ian King wrote: > On 01/07/15 18:12, Emil Velikov wrote: >> On 1 July 2015 at 17:56, Ilia Mirkin wrote: >>> On Wed, Jul 1, 2015 at 12:51 PM, Colin King wrote: >>>> From: Colin Ian King >>>> >>>> Various usif_ioctl helper functions do not initialize the >>>> return variable ret and some of the error handling return >>>> paths just return garbage values that were on the stack (or >>>> in a register). I believe that in all the cases, the >>>> initial ret variable should be set to -EINVAL and subsequent >>>> paths through these helper functions set it appropriately >>>> otherwise. >>>> >>>> Found via static analysis using cppcheck: >>>> >>>> [drivers/gpu/drm/nouveau/nouveau_usif.c:138]: >>>> (error) Uninitialized variable: ret >>> >>> It sure would seem that way, wouldn't it? >>> >>> #define nvif_unpack(d,vl,vh,m) ({ \ >>> if ((vl) == 0 || ret == -ENOSYS) { \ >>> int _size = sizeof(d); \ >>> if (_size <= size && (d).version >= (vl) && \ >>> (d).version <= (vh)) { \ >>> data = (u8 *)data + _size; \ >>> size = size - _size; \ >>> ret = ((m) || !size) ? 0 : -E2BIG; \ >>> } else { \ >>> ret = -ENOSYS; \ >>> } \ >>> } \ >>> (ret == 0); \ >>> }) >>> >>> So actually it does get initialized, and I guess cppcheck doesn't know >>> about macros? > > Hrm, what about the case when ((vl) == 0 || ret == -ENOSYS) is false, > where is ret being set in that case? Is that actually the case for any of the callsites? gcc would complain about that... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/