From patchwork Wed Oct 2 16:40:56 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Herrmann X-Patchwork-Id: 2976011 Return-Path: X-Original-To: patchwork-linux-fbdev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 44EA19F2B8 for ; Wed, 2 Oct 2013 16:41:06 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 91F362010F for ; Wed, 2 Oct 2013 16:41:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5B32920435 for ; Wed, 2 Oct 2013 16:41:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754100Ab3JBQk7 (ORCPT ); Wed, 2 Oct 2013 12:40:59 -0400 Received: from mail-ea0-f180.google.com ([209.85.215.180]:43347 "EHLO mail-ea0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753422Ab3JBQk7 (ORCPT ); Wed, 2 Oct 2013 12:40:59 -0400 Received: by mail-ea0-f180.google.com with SMTP id h10so518561eaj.25 for ; Wed, 02 Oct 2013 09:40:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=EcsrgeDl+2TCKlODXD6psdRtsm898He67ryFTs34WI0=; b=ueeux7Cx5ZJXfDfnzqTo54OfvqorcSZI+i9eVegGOIYzPQICu/YuPHr6jKQXQFkYkQ GVhRz8sP8Y0EOtz3lwGqFrGeNVU7CCvPiSoeMSsQulrXm2MDCloSYBNnF0ud+TiKM19d OXpfcKkx94Ul0vFzR0VAxLrdh5k4ksm4K6d6aFsw6F5doB0GNfrCNiqquoj2CRPTF0SN 0dkx/4HID9nWOscmFlJwmcKuVIeNTskatMIQiRwKjYc+jaD8wR+aYX+t+RA9Wzhqh1NH TqzgjOzFXWszbWdrrf49qLyY+uA8j+1y3SYeulCzzBXDwzXrkW4MN2y0E2suVgHdEIKk 44bQ== X-Received: by 10.14.208.194 with SMTP id q42mr4916006eeo.31.1380732057595; Wed, 02 Oct 2013 09:40:57 -0700 (PDT) Received: from localhost.localdomain (stgt-5f71b885.pool.mediaWays.net. [95.113.184.133]) by mx.google.com with ESMTPSA id z12sm5584592eev.6.1969.12.31.16.00.00 (version=TLSv1.2 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 02 Oct 2013 09:40:56 -0700 (PDT) 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 , James Bates Subject: [PATCH v2] efifb: prevent null-deref when iterating dmi_list Date: Wed, 2 Oct 2013 18:40:56 +0200 Message-Id: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> X-Mailer: git-send-email 1.8.4 Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Spam-Status: No, score=-7.4 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 --- Hi As James didn't respond to the last emails, I just rebased the patch and resent it. The efi M_xyz constants were moved to x86-sysfb so if anyone wants to remove unused bits, please send a separate patch to LKML and x86-ML. This patch just fixes the NULL-deref. Thanks David 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;