linux-kernel - [PATCH] gpu-drm-tiny-cirrus: Add NULL check of pointer pipe->plane.state->fb in cirrus_pipe

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Date:   Wed, 15 Feb 2023 20:15:49 +0300
From:   Alexander Sapozhnikov <alsp705@...il.com>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     Alexandr Sapozhnikov <alsp705@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        Jani Nikula <jani.nikula@...el.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        virtualization@...ts.linux-foundation.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: [PATCH] gpu-drm-tiny-cirrus: Add NULL check of pointer pipe->plane.state->fb in cirrus_pipe_update()

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