drm/ast: potential dereference of null pointer

[ Upstream commit fea3fdf975dd9f3e5248afaab8fe023db313f005 ]

The return value of kzalloc() needs to be checked.
To avoid use of null pointer '&ast_state->base' in case of the
failure of alloc.

Fixes: f0adbc382b8b ("drm/ast: Allocate initial CRTC state of the correct size")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20211214014126.2211535-1-jiasheng@iscas.ac.cn
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index a3c2f76668abeab6bd72f72ea2b622280ba675d9..d27f2840b9555a8272e088e0090be6966889ff1a 100644 (file)
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -857,7 +857,10 @@ static void ast_crtc_reset(struct drm_crtc *crtc)
        if (crtc->state)
                crtc->funcs->atomic_destroy_state(crtc, crtc->state);
 
-       __drm_atomic_helper_crtc_reset(crtc, &ast_state->base);
+       if (ast_state)
+               __drm_atomic_helper_crtc_reset(crtc, &ast_state->base);
+       else
+               __drm_atomic_helper_crtc_reset(crtc, NULL);
 }
 
 static struct drm_crtc_state *