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SubjectRe: [PATCH] drm/msm/dpu: Add check for cstate
From
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 <jiasheng@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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