Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751509Ab3JSKkF (ORCPT ); Sat, 19 Oct 2013 06:40:05 -0400 Received: from mail-ie0-f172.google.com ([209.85.223.172]:39018 "EHLO mail-ie0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750960Ab3JSKkD (ORCPT ); Sat, 19 Oct 2013 06:40:03 -0400 MIME-Version: 1.0 In-Reply-To: <1380732219-5458-1-git-send-email-dh.herrmann@gmail.com> References: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> <1380732219-5458-1-git-send-email-dh.herrmann@gmail.com> Date: Sat, 19 Oct 2013 12:40:02 +0200 Message-ID: Subject: Re: [PATCH v3] efifb: prevent null-deref when iterating dmi_list From: David Herrmann To: "linux-fbdev@vger.kernel.org" Cc: James Bates , linux-kernel , Tomi Valkeinen , Jean-Christophe Plagniol-Villard , David Herrmann Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2192 Lines: 49 ping On Wed, Oct 2, 2013 at 6:43 PM, David Herrmann wrote: > From: James Bates > > The dmi_list array is initialized using gnu designated initializers, and > therefore may contain fewer explicitly defined entries as there are > elements in it. This is because the enum above with M_xyz constants > contains more items than the designated initializer. Those elements not > explicitly initialized are implicitly set to 0. > > Now efifb_setup() loops through all these array elements, and performs > a strcmp on each item. For non explicitly initialized elements this will > be a null pointer: > > This patch swaps the check order in the if statement, thus checks first > whether dmi_list[i].base is null. > > Signed-off-by: James Bates > Signed-off-by: David Herrmann > --- > v3: fixes the "Author" field and James' email address > > drivers/video/efifb.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c > index 7f9ff75..fcb9500 100644 > --- a/drivers/video/efifb.c > +++ b/drivers/video/efifb.c > @@ -108,8 +108,8 @@ static int efifb_setup(char *options) > if (!*this_opt) continue; > > for (i = 0; i < M_UNKNOWN; i++) { > - if (!strcmp(this_opt, efifb_dmi_list[i].optname) && > - efifb_dmi_list[i].base != 0) { > + if (efifb_dmi_list[i].base != 0 && > + !strcmp(this_opt, efifb_dmi_list[i].optname)) { > screen_info.lfb_base = efifb_dmi_list[i].base; > screen_info.lfb_linelength = efifb_dmi_list[i].stride; > screen_info.lfb_width = efifb_dmi_list[i].width; > -- > 1.8.4 > -- 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/