[PATCH] drm/tegra: fix a possible null pointer dereference

[Qiu-ji Chen <chenqiuji666@gmail.com>]

In tegra_crtc_reset(), new memory is allocated with kzalloc(), but
no check is performed. Before calling __drm_atomic_helper_crtc_reset,
state should be checked to prevent possible null pointer dereference.

Fixes: b7e0b04ae450 ("drm/tegra: Convert to using __drm_atomic_helper_crtc_reset() for reset.")
Cc: stable@vger.kernel.org
Signed-off-by: Qiu-ji Chen <chenqiuji666@gmail.com>
---
 drivers/gpu/drm/tegra/dc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index be61c9d1a4f0..1ed30853bd9e 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -1388,7 +1388,10 @@ static void tegra_crtc_reset(struct drm_crtc *crtc)
 	if (crtc->state)
 		tegra_crtc_atomic_destroy_state(crtc, crtc->state);
 
-	__drm_atomic_helper_crtc_reset(crtc, &state->base);
+	if (state)
+		 __drm_atomic_helper_crtc_reset(crtc, &state->base);
+	else
+		 __drm_atomic_helper_crtc_reset(crtc, NULL);
 }
 
 static struct drm_crtc_state *
-- 
2.34.1