From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933127AbeBVQLg (ORCPT ); Thu, 22 Feb 2018 11:11:36 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:39570 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932952AbeBVQLe (ORCPT ); Thu, 22 Feb 2018 11:11:34 -0500 X-Google-Smtp-Source: AH8x225AZpN/yZ2aoCiCNzg/JRFLPEXoYxHVsXgNe83gkL0gkNFejulq4Q/igprTCVjX+vBBYfeYSg== Date: Thu, 22 Feb 2018 17:11:28 +0100 From: Daniel Vetter To: Oleksandr Andrushchenko Cc: Oleksandr Andrushchenko , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, daniel.vetter@intel.com, airlied@linux.ie Subject: Re: [PATCH v1] drm/simple_kms_helper: Fix NULL pointer dereference with no active CRTC Message-ID: <20180222161128.GC6419@phenom.ffwll.local> Mail-Followup-To: Oleksandr Andrushchenko , Oleksandr Andrushchenko , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, daniel.vetter@intel.com, airlied@linux.ie References: <1519279759-7803-1-git-send-email-andr2000@gmail.com> <1f051697-468d-76b9-a2be-16a281f57249@epam.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1f051697-468d-76b9-a2be-16a281f57249@epam.com> X-Operating-System: Linux phenom 4.14.0-3-amd64 User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 22, 2018 at 08:12:48AM +0200, Oleksandr Andrushchenko wrote: > On 02/22/2018 08:09 AM, Oleksandr Andrushchenko wrote: > > From: Oleksandr Andrushchenko > > > > It is possible that drm_simple_kms_plane_atomic_check called > > with no CRTC set, e.g. when user-space application sets CRTC_ID/FB_ID > > to 0 before doing any actual drawing. This leads to NULL pointer > > dereference because in this case new CRTC state is NULL and must be > > checked before accessing. > > > > Signed-off-by: Oleksandr Andrushchenko > > Reviewed-by: Daniel Vetter > > > > --- > > Changes since initial: > > - re-worked checks for null CRTC as suggested by Daniel Vetter > > --- > > drivers/gpu/drm/drm_simple_kms_helper.c | 10 +++------- > > 1 file changed, 3 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c > > index 9ca8a4a59b74..4a1dbd88b1ec 100644 > > --- a/drivers/gpu/drm/drm_simple_kms_helper.c > > +++ b/drivers/gpu/drm/drm_simple_kms_helper.c > > @@ -121,12 +121,6 @@ static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane, > > pipe = container_of(plane, struct drm_simple_display_pipe, plane); > > crtc_state = drm_atomic_get_new_crtc_state(plane_state->state, > > &pipe->crtc); > > - if (!crtc_state->enable) > > - return 0; /* nothing to check when disabling or disabled */ > > - > > - if (crtc_state->enable) > > - drm_mode_get_hv_timing(&crtc_state->mode, > > - &clip.x2, &clip.y2); > > ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state, > > &clip, > > @@ -137,7 +131,9 @@ static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane, > > return ret; > > if (!plane_state->visible) > > - return -EINVAL; > Daniel, I have put your R-b tag, but I had removed suggested > "WARN_ON(crtc_state && crtc_state->enable);" > here as it fires each time when crtc_state is not NULL. > Please let me know if this is not ok and you want me to remove > your R-b tag. I'm a bit confused why that fires, but oh well. Applied, thanks for your patch. -Daniel > > + return 0; > > + > > + drm_mode_get_hv_timing(&crtc_state->mode, &clip.x2, &clip.y2); > > if (!pipe->funcs || !pipe->funcs->check) > > return 0; > Thank you, > Oleksandr > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch