From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754663Ab3JBQnp (ORCPT ); Wed, 2 Oct 2013 12:43:45 -0400 Received: from mail-ea0-f176.google.com ([209.85.215.176]:62446 "EHLO mail-ea0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753659Ab3JBQnm (ORCPT ); Wed, 2 Oct 2013 12:43:42 -0400 From: David Herrmann To: linux-fbdev@vger.kernel.org Cc: James Bates , linux-kernel@vger.kernel.org, Tomi Valkeinen , Jean-Christophe Plagniol-Villard , David Herrmann Subject: [PATCH v3] efifb: prevent null-deref when iterating dmi_list Date: Wed, 2 Oct 2013 18:43:39 +0200 Message-Id: <1380732219-5458-1-git-send-email-dh.herrmann@gmail.com> X-Mailer: git-send-email 1.8.4 In-Reply-To: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> References: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Herrmann Date: Wed, 02 Oct 2013 16:43:39 +0000 Subject: [PATCH v3] efifb: prevent null-deref when iterating dmi_list Message-Id: <1380732219-5458-1-git-send-email-dh.herrmann@gmail.com> List-Id: References: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> In-Reply-To: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-fbdev@vger.kernel.org Cc: James Bates , linux-kernel@vger.kernel.org, Tomi Valkeinen , Jean-Christophe Plagniol-Villard , David Herrmann 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