Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754668AbaGBWSl (ORCPT ); Wed, 2 Jul 2014 18:18:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30627 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751303AbaGBWSk (ORCPT ); Wed, 2 Jul 2014 18:18:40 -0400 Date: Wed, 2 Jul 2014 18:18:22 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Rickard Strandqvist cc: Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Jingoo Han , Alexandru Juncu , Daniel Vetter , Joe Perches , linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] video: fbdev: matrox: matroxfb_base.c: Fix for possible null pointer dereference In-Reply-To: <1404337551-6499-1-git-send-email-rickard_strandqvist@spectrumdigital.se> Message-ID: References: <1404337551-6499-1-git-send-email-rickard_strandqvist@spectrumdigital.se> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2 Jul 2014, Rickard Strandqvist wrote: > Fix a possible null pointer dereference, there is otherwise a risk of a > possible null pointer dereference > > This was found using a static code analysis program called cppcheck > > Signed-off-by: Rickard Strandqvist > --- > drivers/video/fbdev/matrox/matroxfb_base.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/fbdev/matrox/matroxfb_base.c b/drivers/video/fbdev/matrox/matroxfb_base.c > index 7116c53..85ef84b 100644 > --- a/drivers/video/fbdev/matrox/matroxfb_base.c > +++ b/drivers/video/fbdev/matrox/matroxfb_base.c > @@ -1971,9 +1971,9 @@ static void matroxfb_register_device(struct matrox_fb_info* minfo) { > int i = 0; > list_add(&minfo->next_fb, &matroxfb_list); > for (drv = matroxfb_driver_l(matroxfb_driver_list.next); > - drv != matroxfb_driver_l(&matroxfb_driver_list); > + drv && drv != matroxfb_driver_l(&matroxfb_driver_list); The "drv" check is pointless because drv can't be NULL - use the patch below. > drv = matroxfb_driver_l(drv->node.next)) { > - if (drv && drv->probe) { > + if (drv->probe) { > void *p = drv->probe(minfo); > if (p) { > minfo->drivers_data[i] = p; > -- > 1.7.10.4 matroxfb: delete pointless NULL-pointer check The for loop walks a double-linked list, so drv cannot be NULL. This patch deletes the pointless NULL-pointer check. cppcheck warned about it. Signed-off-by: Mikulas Patocka --- drivers/video/fbdev/matrox/matroxfb_base.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/drivers/video/fbdev/matrox/matroxfb_base.c =================================================================== --- linux-2.6.orig/drivers/video/fbdev/matrox/matroxfb_base.c 2014-06-19 16:41:45.048259897 +0200 +++ linux-2.6/drivers/video/fbdev/matrox/matroxfb_base.c 2014-07-03 00:13:04.299380130 +0200 @@ -1973,7 +1973,7 @@ static void matroxfb_register_device(str for (drv = matroxfb_driver_l(matroxfb_driver_list.next); drv != matroxfb_driver_l(&matroxfb_driver_list); drv = matroxfb_driver_l(drv->node.next)) { - if (drv && drv->probe) { + if (drv->probe) { void *p = drv->probe(minfo); if (p) { minfo->drivers_data[i] = p; -- 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/