linux-kernel - [PATCH AUTOSEL 6.1 01/29] drm/cirrus: NULL-check pipe->plane.state->fb in cirrus_pipe

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Message-Id: <20230320005413.1428452-1-sashal@kernel.org>
Date:   Sun, 19 Mar 2023 20:53:43 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Alexandr Sapozhnikov <alsp705@...il.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Sasha Levin <sashal@...nel.org>, airlied@...hat.com,
        kraxel@...hat.com, airlied@...il.com, daniel@...ll.ch,
        sam@...nborg.org, jani.nikula@...el.com, javierm@...hat.com,
        ville.syrjala@...ux.intel.com,
        virtualization@...ts.linux-foundation.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.1 01/29] drm/cirrus: NULL-check pipe->plane.state->fb in cirrus_pipe_update()

From: Alexandr Sapozhnikov <alsp705@...il.com>

[ Upstream commit 7245e629dcaaf308f1868aeffa218e9849c77893 ]

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.

v2:
	* aligned commit message to line-length limits

Signed-off-by: Alexandr Sapozhnikov <alsp705@...il.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230215171549.16305-1-alsp705@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 354d5e854a6f0..b27e469e90217 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);
 }
 
-- 
2.39.2