From:   Jiasheng Jiang <jiasheng@iscas.ac.cn>
To:     hjc@rock-chips.com, heiko@sntech.de, airlied@linux.ie,
        daniel@ffwll.ch, p.zabel@pengutronix.de
Cc:     dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
        Jiasheng Jiang <jiasheng@iscas.ac.cn>
Subject: [PATCH] drm/rockchip: Check for NULL pointer after calling kzalloc
Date:   Fri, 14 Jan 2022 17:30:15 +0800
Message-Id: <20220114093015.1295274-1-jiasheng@iscas.ac.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

As the possible failure of the kzalloc(), crtc_state could be NULL
pointer.
Therefore, it should be better to check it in order to avoid the
dereference of the NULL pointer, like the kzalloc() in
vop_crtc_duplicate_state().
If fails, we can directly use the 'NULL' instead of the
'&crtc_state->base' and __drm_atomic_helper_crtc_duplicate_state() will
deal with it correctly.

Fixes: dc0b408f5a87 ("drm/rockchip: allocate correct crtc state structure on reset")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index 3e8d9e2d1b67..db672ff5e37b 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1577,7 +1577,10 @@ static void vop_crtc_reset(struct drm_crtc *crtc)
 	if (crtc->state)
 		vop_crtc_destroy_state(crtc, crtc->state);
 
-	__drm_atomic_helper_crtc_reset(crtc, &crtc_state->base);
+	if (!crtc_state)
+		__drm_atomic_helper_crtc_reset(crtc, NULL);
+	else
+		__drm_atomic_helper_crtc_reset(crtc, &crtc_state->base);
 }
 
 #ifdef CONFIG_DRM_ANALOGIX_DP
-- 
2.25.1