Re: [PATCH] drm/exynos: gsc: Variable "gscblk_cfg" in function gsc_set_gscblk_fimd_wb() could be uninitialized

[Marek Szyprowski]

Hi

On 2019-01-28 19:28, Yizhuo wrote:
> In function gsc_set_gscblk_fimd_wb(), local variable "gscblk_cfg"
> could be uninitialized of function regmap_read returns -EINVAL.
> However, this value will be  write to the register after "or"
> operation. This is potentially unsafe.
>
> Signed-off-by: Yizhuo <yzhai003@xxxxxxx>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_gsc.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gsc.c b/drivers/gpu/drm/exynos/exynos_drm_gsc.c
> index 0506b2b17ac1..b1d0f974fe80 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gsc.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gsc.c
> @@ -441,11 +441,16 @@ static int gsc_sw_reset(struct gsc_context *ctx)
>  static void gsc_set_gscblk_fimd_wb(struct gsc_context *ctx, bool enable)

This function has been completely removed in mainline kernel by commit
8b7d3ec83aba ("drm/exynos: gsc: Convert driver to IPP v2 core API"), so
there is no need for any fix anymore.

>  {
>  	unsigned int gscblk_cfg;
> +	int ret;
>  
>  	if (!ctx->sysreg)
>  		return;
>  
> -	regmap_read(ctx->sysreg, SYSREG_GSCBLK_CFG1, &gscblk_cfg);
> +	ret = regmap_read(ctx->sysreg, SYSREG_GSCBLK_CFG1, &gscblk_cfg);
> +	if (ret) {
> +		DRM_ERROR("gsc: Fail to read system register\n");
> +		return;
> +	}
>  
>  	if (enable)
>  		gscblk_cfg |= GSC_BLK_DISP1WB_DEST(ctx->id) |

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland