From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E975C31E5B for ; Tue, 18 Jun 2019 22:38:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 738FC2084D for ; Tue, 18 Jun 2019 22:38:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730738AbfFRWi5 (ORCPT ); Tue, 18 Jun 2019 18:38:57 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:34309 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730176AbfFRWi4 (ORCPT ); Tue, 18 Jun 2019 18:38:56 -0400 Received: from 162-237-133-238.lightspeed.rcsntx.sbcglobal.net ([162.237.133.238] helo=lindsey) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1hdMke-0004ks-Dk; Tue, 18 Jun 2019 22:38:52 +0000 Date: Tue, 18 Jun 2019 17:38:49 -0500 From: Tyler Hicks To: Jani Nikula Cc: Gen Zhang , sean@poorly.run, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH] drm_edid-load: Fix a missing-check bug in drivers/gpu/drm/drm_edid_load.c Message-ID: <20190618223848.GD6248@lindsey> References: <20190522123920.GB6772@zhanggen-UX430UQ> <87o93u7d3s.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87o93u7d3s.fsf@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-05-22 17:55:35, Jani Nikula wrote: > On Wed, 22 May 2019, Gen Zhang wrote: > > In drm_load_edid_firmware(), fwstr is allocated by kstrdup(). And fwstr > > is dereferenced in the following codes. However, memory allocation > > functions such as kstrdup() may fail and returns NULL. Dereferencing > > this null pointer may cause the kernel go wrong. Thus we should check > > this kstrdup() operation. > > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > > the caller site. > > strsep() handles the NULL pointer just fine, so there won't be a NULL > dereference. However this patch seems like the right thing to do anyway. I came across this thread while triaging CVE-2019-12382. I agree that the code before was fine but more complex than necessary. There's no real security impact here since a NULL pointer dereference was not possible. I've requested that MITRE reject CVE-2019-12382. This change is a nice improvement, though. Tyler > > Reviewed-by: Jani Nikula > > > > > Signed-off-by: Gen Zhang > > > > --- > > diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c > > index a491509..a0e107a 100644 > > --- a/drivers/gpu/drm/drm_edid_load.c > > +++ b/drivers/gpu/drm/drm_edid_load.c > > @@ -290,6 +290,8 @@ struct edid *drm_load_edid_firmware(struct drm_connector *connector) > > * the last one found one as a fallback. > > */ > > fwstr = kstrdup(edid_firmware, GFP_KERNEL); > > + if (!fwstr) > > + return ERR_PTR(-ENOMEM); > > edidstr = fwstr; > > > > while ((edidname = strsep(&edidstr, ","))) { > > --- > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Jani Nikula, Intel Open Source Graphics Center