linux-kernel - [PATCH] drm/rockchip: Check for NULL pointer after calling kzalloc

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Date:   Fri, 14 Jan 2022 17:30:15 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     hjc@...k-chips.com, heiko@...ech.de, airlied@...ux.ie,
        daniel@...ll.ch, p.zabel@...gutronix.de
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH] drm/rockchip: Check for NULL pointer after calling kzalloc

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@...as.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