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

[baihaowen]

在 2022/5/30 下午3:33, Haowen Bai 写道:
> The ctx->hw is dereferencing before null checking, so move
> it after checking.
>
> Signed-off-by: Haowen Bai <baihaowen@xxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.c
> index bcccce292937..e59680cdd0ce 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.c
> @@ -155,11 +155,13 @@ static void dpu_hw_wb_roi(struct dpu_hw_wb *ctx, struct dpu_hw_wb_cfg *wb)
>  static void dpu_hw_wb_setup_qos_lut(struct dpu_hw_wb *ctx,
>  		struct dpu_hw_wb_qos_cfg *cfg)
>  {
> -	struct dpu_hw_blk_reg_map *c = &ctx->hw;
> +	struct dpu_hw_blk_reg_map *c;
>  	u32 qos_ctrl = 0;
>  
>  	if (!ctx || !cfg)
>  		return;
> +	
> +	c = &ctx->hw;
>  
>  	DPU_REG_WRITE(c, WB_DANGER_LUT, cfg->danger_lut);
>  	DPU_REG_WRITE(c, WB_SAFE_LUT, cfg->safe_lut);
Sorry, plz ignore this patch.

ctx->hw is dereferenced, &ctx->hw is just a pointer math for pointer address offset, so it would not cause a bug(dereferencing null pointer).

 

-- 
Haowen Bai