Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752500AbbGARSf (ORCPT ); Wed, 1 Jul 2015 13:18:35 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:58231 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752671AbbGARS1 (ORCPT ); Wed, 1 Jul 2015 13:18:27 -0400 Message-ID: <559420DA.3010401@canonical.com> Date: Wed, 01 Jul 2015 18:18:18 +0100 From: Colin Ian King User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Emil Velikov , Ilia Mirkin CC: Ben Skeggs , "dri-devel@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] drm/nouveau: usif_ioctl: ensure returns are initialized References: <1435769495-2025-1-git-send-email-colin.king@canonical.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2672 Lines: 56 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? >> > I think I'm having deja-vu, but I do recall a similar mention to Ben. > Although in my defence I've assumed that nvif_unpack was a function, > as macros normally are normally all caps. Seems like the patch that > capitalises nvif_unpack never made it upstream :'-( > > Cheers, > Emil > -- 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/