Re: [PATCH 7/7] media: cedrus: validate HEVC slice reference lists

["Jernej Škrabec" <jernej.skrabec@gmail.com>]

Dne ponedeljek, 23. marec 2026 ob 08:03:14 Srednjeevropski standardni čas je Pengpeng Hou napisal(a):
> Cedrus consumes HEVC slice parameters directly from stateless V4L2
> controls, but it does not validate the active reference counts or the
> ref_idx_l0/ref_idx_l1 values before using them in fixed-size 16-entry
> reference arrays. Oversized counts or indices can therefore walk past
> the end of those arrays in the HEVC decode path.
> 
> Reject HEVC slice controls whose active reference counts or reference
> indices exceed V4L2_HEVC_DPB_ENTRIES_NUM_MAX.
> 
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>

There is nothing Cedrus specific here. Why not move it to common code?

Best regards,
Jernej

> ---
>  drivers/staging/media/sunxi/cedrus/cedrus.c | 22 +++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.c b/drivers/staging/media/sunxi/cedrus/cedrus.c
> index 6600245dff0e..d68da1eaa7aa 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus.c
> @@ -77,6 +77,28 @@ static int cedrus_try_ctrl(struct v4l2_ctrl *ctrl)
>  			ctx->bit_depth = bit_depth;
>  			cedrus_reset_cap_format(ctx);
>  		}
> +	} else if (ctrl->id == V4L2_CID_STATELESS_HEVC_SLICE_PARAMS) {
> +		const struct v4l2_ctrl_hevc_slice_params *slice = ctrl->p_new.p_hevc_slice_params;
> +		unsigned int i;
> +
> +		if (slice->num_ref_idx_l0_active_minus1 >=
> +		    V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
> +			return -EINVAL;
> +
> +		for (i = 0; i <= slice->num_ref_idx_l0_active_minus1; i++)
> +			if (slice->ref_idx_l0[i] >= V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
> +				return -EINVAL;
> +
> +		if (slice->slice_type == V4L2_HEVC_SLICE_TYPE_B) {
> +			if (slice->num_ref_idx_l1_active_minus1 >=
> +			    V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
> +				return -EINVAL;
> +
> +			for (i = 0; i <= slice->num_ref_idx_l1_active_minus1; i++)
> +				if (slice->ref_idx_l1[i] >=
> +				    V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
> +					return -EINVAL;
> +		}
>  	}
>  
>  	return 0;
>