Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 116C3C433EF for ; Wed, 1 Dec 2021 13:29:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349439AbhLANcW (ORCPT ); Wed, 1 Dec 2021 08:32:22 -0500 Received: from foss.arm.com ([217.140.110.172]:37062 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232967AbhLANcT (ORCPT ); Wed, 1 Dec 2021 08:32:19 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 13B466D; Wed, 1 Dec 2021 05:28:57 -0800 (PST) Received: from e110455-lin.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E78633F5A1; Wed, 1 Dec 2021 05:28:56 -0800 (PST) Received: by e110455-lin.cambridge.arm.com (Postfix, from userid 1000) id A84C1684474; Wed, 1 Dec 2021 13:28:55 +0000 (GMT) Date: Wed, 1 Dec 2021 13:28:55 +0000 From: Liviu Dudau To: Zhou Qingyang Cc: kjlu@umn.edu, "James (Qian) Wang" , Mihail Atanassov , Brian Starkey , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] drm/komeda: Fix an undefined behavior bug in komeda_plane_add() Message-ID: References: <20211201033704.32054-1-zhou1615@umn.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211201033704.32054-1-zhou1615@umn.edu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 01, 2021 at 11:37:03AM +0800, Zhou Qingyang wrote: > In komeda_plane_add(), komeda_get_layer_fourcc_list() is assigned to > formats and used in drm_universal_plane_init(). > drm_universal_plane_init() passes formats to > __drm_universal_plane_init(). __drm_universal_plane_init() further > passes formats to memcpy() as src parameter, which could lead to an > undefined behavior bug on failure of komeda_get_layer_fourcc_list(). > > Fix this bug by adding a check of formats. > > This bug was found by a static analyzer. The analysis employs > differential checking to identify inconsistent security operations > (e.g., checks or kfrees) between two code paths and confirms that the > inconsistent operations are not recovered in the current function or > the callers, so they constitute bugs. > > Note that, as a bug found by static analysis, it can be a false > positive or hard to trigger. Multiple researchers have cross-reviewed > the bug. > > Builds with CONFIG_DRM_KOMEDA=m show no new warnings, > and our static analyzer no longer warns about this code. > > Fixes: 61f1c4a8ab75 ("drm/komeda: Attach komeda_dev to DRM-KMS") > Signed-off-by: Zhou Qingyang Thanks for the fix! Reviewed-by: Liviu Dudau Best regards, Liviu > --- > Changes in v2 > - Use kfree and return instead of using 'goto' > > drivers/gpu/drm/arm/display/komeda/komeda_plane.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_plane.c b/drivers/gpu/drm/arm/display/komeda/komeda_plane.c > index d63d83800a8a..aa193c58f4bf 100644 > --- a/drivers/gpu/drm/arm/display/komeda/komeda_plane.c > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_plane.c > @@ -265,6 +265,10 @@ static int komeda_plane_add(struct komeda_kms_dev *kms, > > formats = komeda_get_layer_fourcc_list(&mdev->fmt_tbl, > layer->layer_type, &n_formats); > + if (!formats) { > + kfree(kplane); > + return -ENOMEM; > + } > > err = drm_universal_plane_init(&kms->base, plane, > get_possible_crtcs(kms, c->pipeline), > -- > 2.25.1 > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯