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From fea3fdf975dd9f3e5248afaab8fe023db313f005 Mon Sep 17 00:00:00 2001
From: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Date: Tue, 14 Dec 2021 09:41:26 +0800
Subject: [PATCH] drm/ast: potential dereference of null pointer
Git-commit: fea3fdf975dd9f3e5248afaab8fe023db313f005
Patch-mainline: v5.16-rc6
References: git-fixes

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
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/ast/ast_mode.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 1e30eaeb0e1b..d5c98f79d58d 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -1121,7 +1121,10 @@ 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 *
-- 
2.31.1