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

[Rob Clark]

On Mon, May 30, 2022 at 12:34 AM Haowen Bai <baihaowen@xxxxxxxxx> wrote:
>
> 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;

tbh, we should just drop both of these null checks.. there is no
codepath that can reach this with potential for either param to be
NULL

BR,
-R

>
>         DPU_REG_WRITE(c, WB_DANGER_LUT, cfg->danger_lut);
>         DPU_REG_WRITE(c, WB_SAFE_LUT, cfg->safe_lut);
> --
> 2.7.4
>