On 06/12/2022 10:05, Jiasheng Jiang wrote:
As kzalloc may fail and return NULL pointer,
it should be better to check cstate
in order to avoid the NULL pointer dereference
in __drm_atomic_helper_crtc_reset.

Fixes: 1cff7440a86e ("drm/msm: Convert to using __drm_atomic_helper_crtc_reset() for 
reset.")
Signed-off-by: Jiasheng Jiang <jiash...@iscas.ac.cn>
---
  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 5 ++++-
  1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c 
b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 13ce321283ff..22c2787b7b38 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -968,7 +968,10 @@ static void dpu_crtc_reset(struct drm_crtc *crtc)
        if (crtc->state)
                dpu_crtc_destroy_state(crtc, crtc->state);
- __drm_atomic_helper_crtc_reset(crtc, &cstate->base);
+       if (cstate)
+               __drm_atomic_helper_crtc_reset(crtc, &cstate->base);
+       else
+               __drm_atomic_helper_crtc_reset(crtc, NULL);

NAK.

The proper fix is to add the if() but to skip the else clause. We should not reset the crtc's state if memory allocation failed.

  }
/**

--
With best wishes
Dmitry

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