Re: [PATCH v3 6/9] media: verisilicon: rockchip: guard VPU981 AV1 divisor and tile buffer

[Benjamin Gaignard <benjamin.gaignard@collabora.com>]

Le 17/06/2026 à 04:19, Michael Bommarito a écrit :
> rockchip_vpu981_av1_dec_set_tile_info() divides context_update_tile_id by
> tile_info->tile_cols and writes one descriptor per tile into the tile_info
> DMA buffer, which holds AV1_MAX_TILES entries; tile_cols and tile_rows
> come from the bitstream. Guard the division against a zero tile_cols by
> initialising the context-update values to zero and computing them only
> when tile_cols is non-zero, and stop the descriptor writes once the
> tile_info buffer is full. The tile geometry written to the hardware
> registers is left unmodified; the per-dimension and total tile bounds are
> enforced by the control validation.
>
> Fixes: 727a400686a2 ("media: verisilicon: Add Rockchip AV1 decoder")
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>

Reviewed-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>

> ---
>   .../verisilicon/rockchip_vpu981_hw_av1_dec.c  | 32 +++++++++++++++----
>   1 file changed, 26 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c b/drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c
> index e4e21ad373233..fd00dbd79fe46 100644
> --- a/drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c
> +++ b/drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c
> @@ -578,16 +578,30 @@ static void rockchip_vpu981_av1_dec_set_tile_info(struct hantro_ctx *ctx)
>   	const struct v4l2_av1_tile_info *tile_info = &ctrls->frame->tile_info;
>   	const struct v4l2_ctrl_av1_tile_group_entry *group_entry =
>   	    ctrls->tile_group_entry;
> -	int context_update_y =
> -	    tile_info->context_update_tile_id / tile_info->tile_cols;
> -	int context_update_x =
> -	    tile_info->context_update_tile_id % tile_info->tile_cols;
> -	int context_update_tile_id =
> -	    context_update_x * tile_info->tile_rows + context_update_y;
> +	int context_update_y = 0;
> +	int context_update_x = 0;
> +	int context_update_tile_id = 0;
>   	u8 *dst = av1_dec->tile_info.cpu;
> +	u8 *dst_end = dst + av1_dec->tile_info.size;
>   	struct hantro_dev *vpu = ctx->dev;
>   	int tile0, tile1;
>   
> +	/*
> +	 * tile_cols and tile_rows are bounded by the V4L2 control validation
> +	 * (V4L2_AV1_MAX_TILE_{COLS,ROWS} and V4L2_AV1_MAX_TILE_COUNT). Guard
> +	 * the divisor here, and keep the descriptor writes within the
> +	 * AV1_MAX_TILES tile_info buffer below; the register values use the
> +	 * unmodified tile geometry.
> +	 */
> +	if (tile_info->tile_cols) {
> +		context_update_y =
> +		    tile_info->context_update_tile_id / tile_info->tile_cols;
> +		context_update_x =
> +		    tile_info->context_update_tile_id % tile_info->tile_cols;
> +		context_update_tile_id =
> +		    context_update_x * tile_info->tile_rows + context_update_y;
> +	}
> +
>   	memset(dst, 0, av1_dec->tile_info.size);
>   
>   	for (tile0 = 0; tile0 < tile_info->tile_cols; tile0++) {
> @@ -598,6 +612,10 @@ static void rockchip_vpu981_av1_dec_set_tile_info(struct hantro_ctx *ctx)
>   			    tile_info->height_in_sbs_minus_1[tile1] + 1;
>   			u32 x0 = tile_info->width_in_sbs_minus_1[tile0] + 1;
>   
> +			/* Stop once the tile_info descriptor buffer is full. */
> +			if (dst + 16 > dst_end)
> +				break;
> +
>   			/* tile size in SB units (width,height) */
>   			*dst++ = x0;
>   			*dst++ = 0;
> @@ -622,6 +640,8 @@ static void rockchip_vpu981_av1_dec_set_tile_info(struct hantro_ctx *ctx)
>   			*dst++ = (end >> 16) & 255;
>   			*dst++ = (end >> 24) & 255;
>   		}
> +		if (dst + 16 > dst_end)
> +			break;
>   	}
>   
>   	hantro_reg_write(vpu, &av1_multicore_expect_context_update, !!(context_update_x == 0));