From:   Alexander Sapozhnikov <alsp705@gmail.com>
To:     Thomas Zimmermann <tzimmermann@suse.de>
Cc:     Alexandr Sapozhnikov <alsp705@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= 
        <ville.syrjala@linux.intel.com>,
        Jani Nikula <jani.nikula@intel.com>,
        Javier Martinez Canillas <javierm@redhat.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        virtualization@lists.linux-foundation.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        lvc-project@linuxtesting.org
Subject: [PATCH] gpu-drm-tiny-cirrus: Add NULL check of pointer pipe->plane.state->fb in cirrus_pipe_update()
Date:   Wed, 15 Feb 2023 20:15:49 +0300
Message-Id: <20230215171549.16305-1-alsp705@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Alexandr Sapozhnikov <alsp705@gmail.com>

After having been compared to NULL value at cirrus.c:455, pointer 'pipe->plane.state->fb' is passed as
1st parameter in call to function 'cirrus_fb_blit_rect' at cirrus.c:461, where it is dereferenced at cirrus.c:316.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Alexandr Sapozhnikov <alsp705@gmail.com>
---
 drivers/gpu/drm/tiny/cirrus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
index 678c2ef..ffa7e61 100644
--- a/drivers/gpu/drm/tiny/cirrus.c
+++ b/drivers/gpu/drm/tiny/cirrus.c
@@ -455,7 +455,7 @@ static void cirrus_pipe_update(struct drm_simple_display_pipe *pipe,
 	if (state->fb && cirrus->cpp != cirrus_cpp(state->fb))
 		cirrus_mode_set(cirrus, &crtc->mode, state->fb);
 
-	if (drm_atomic_helper_damage_merged(old_state, state, &rect))
+	if (state->fb && drm_atomic_helper_damage_merged(old_state, state, &rect))
 		cirrus_fb_blit_rect(state->fb, &shadow_plane_state->data[0], &rect);
 }
 
-- 
2.5.3