Re: [PATCH] drm/msm/dpu: Fix pointer dereferenced before checking

[Abhinav Kumar <quic_abhinavk@quicinc.com>]

On 5/29/2022 7:19 PM, Haowen Bai wrote:
> The phys_enc->wb_idx is dereferencing before null checking, so move
> it after checking.
> 
> Signed-off-by: Haowen Bai <baihaowen@meizu.com>

Fixes: d7d0e73f7de33 ("drm/msm/dpu: introduce the dpu_encoder_phys_* for 
writeback")

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>

> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> index 4829d1ce0cf8..59da348ff339 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> @@ -574,11 +574,11 @@ static void dpu_encoder_phys_wb_disable(struct dpu_encoder_phys *phys_enc)
>    */
>   static void dpu_encoder_phys_wb_destroy(struct dpu_encoder_phys *phys_enc)
>   {
> -	DPU_DEBUG("[wb:%d]\n", phys_enc->wb_idx - WB_0);
> -
>   	if (!phys_enc)
>   		return;
>   
> +	DPU_DEBUG("[wb:%d]\n", phys_enc->wb_idx - WB_0);
> +
>   	kfree(phys_enc);
>   }
>