Re: [PATCH v3 08/17] media: apple: avd: add vp9 support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 5 potential issue(s) to consider:
- [High] media: apple: avd: check vb2_plane_vaddr() return value in set_tiles()
- [High] media: apple: avd: scratch buffer sizing mismatch in avd_vp9_alloc_bufs()
- [High] media: apple: avd: tile coordinate underflow and truncation in set_tiles()
- [Medium] media: apple: avd: fix VP9_REF_SEL_ALT selection logic in make_flags1()
- [Medium] media: apple: avd: uninitialized vp9 ref dimensions in set_refs() after failed run
--

commit 9bf6a8642d1822a5f7e33f39bed4085dfd22aa1e
Author: Sofus Forstreuter <sofus.c@icloud.com>

media: apple: avd: add vp9 support

This commit adds stateless VP9 hardware video decoding support to the Apple
Video Decoder (AVD) V4L2 driver.

> diff --git a/drivers/media/platform/apple/avd/avd-vp9.c b/drivers/media/platform/apple/avd/avd-vp9.c
> new file mode 100644
> index 0000000000000..fe2d58e6ac63d
> --- /dev/null
> +++ b/drivers/media/platform/apple/avd/avd-vp9.c
> @@ -0,0 +1,1054 @@

[ ... ]

> +static void set_refs(struct avd_ctx *ctx, struct avd_vp9_run *run)
> +{
> +	const struct v4l2_ctrl_vp9_frame *frame = run->decode_params;
> +	struct avd_decoded_buffer *dst, *ref_buf[4];
> +	dma_addr_t addr;
> +	int xscale, yscale;
> +
> +	dst = vb2_to_avd_decoded_buf(&run->base.bufs.dst->vb2_buf);
> +
> +	ref_buf[0] = avd_get_ref_buf(ctx, &dst->base.vb, frame->last_frame_ts);
> +	ref_buf[1] =
> +		avd_get_ref_buf(ctx, &dst->base.vb, frame->golden_frame_ts);
> +	ref_buf[2] = avd_get_ref_buf(ctx, &dst->base.vb, frame->alt_frame_ts);
> +
> +	push(0, "");
> +	push(0, "");
> +	push(0, "");
> +
> +	for (int i = 0; i < V4L2_VP9_NUM_FRAME_CTX - 1; i++) {
> +		addr = vb2_dma_contig_plane_dma_addr(
> +			       &ref_buf[i]->base.vb.vb2_buf, 0) +
> +		       ref_buf[i]->comp.start_offset;
> +
> +		push(AVD_REF_FLAG_CONST, "hdr_9c_ref_100");
> +		push(AVD_HDR_HEIGHT(ref_buf[i]->vp9.height - 1) |
> +			     AVD_HDR_WIDTH(ref_buf[i]->vp9.width - 1),
> +		     "hdr_70_ref_height_width");

[Severity: Medium]
Can ref_buf[i]->vp9.height and ref_buf[i]->vp9.width be 0 here if an earlier
decode run failed?

In avd_vp9_run(), avd_vp9_run_preamble() calls avd_run_preamble() first, which
copies the timestamp to dst and sets copied_timestamp = 1 via
v4l2_m2m_buf_copy_metadata(). However, update_dec_buf_info() is only called
later in avd_vp9_run() after both validate_dec_params() and avd_init_job()
succeed.

If validate_dec_params() or avd_init_job() fails on a newly allocated capture
buffer, the buffer is returned with VB2_BUF_STATE_ERROR while retaining its
copied timestamp and leaving vp9.width and vp9.height as 0. If a subsequent
inter-frame references that timestamp, avd_get_ref_buf() matches that capture
buffer via vb2_find_buffer(), causing ref_buf[i]->vp9.height - 1 and
ref_buf[i]->vp9.width - 1 to underflow to 0xffff.

> +
> +		xscale = (ref_buf[i]->vp9.width << VP9_REF_SCALE_SHIFT) /
> +			 dst->vp9.width;
> +		yscale = (ref_buf[i]->vp9.height << VP9_REF_SCALE_SHIFT) /
> +			 dst->vp9.height;
> +		push(AVD_HDR_HEIGHT(xscale) | AVD_HDR_WIDTH(yscale),
> +		     "ref_scale");
> +
> +		push_comp(ctx, addr, ref_buf[i]->comp.offsets);
> +	}
> +}
> +
> +static u32 make_flags1(struct avd_ctx *ctx, struct avd_vp9_run *run)
> +{
> +	struct avd_vp9_ctx *vp9_ctx = ctx->priv;
> +	const struct v4l2_ctrl_vp9_frame *frame = run->decode_params;
> +	struct avd_decoded_buffer *dst, *last, *golden, *alt;
> +
> +	dst = vb2_to_avd_decoded_buf(&run->base.bufs.dst->vb2_buf);
> +	last = avd_get_ref_buf(ctx, &dst->base.vb, frame->last_frame_ts);
> +	golden = avd_get_ref_buf(ctx, &dst->base.vb, frame->golden_frame_ts);
> +	alt = avd_get_ref_buf(ctx, &dst->base.vb, frame->alt_frame_ts);
> +	u32 flags;
> +
> +	/*
> +	 * i have only seen V4L2_VP9_SIGN_BIAS_ALT, im simply guessing the
> +	 * same applies for last and golden
> +	 */
> +	flags = VP9_REF_SEL_LAST(VP9_LAST_FRAME);
> +
> +	flags |= VP9_REF_BIAS_LAST(frame->ref_frame_sign_bias &
> +				   V4L2_VP9_SIGN_BIAS_LAST);
> +	flags |= VP9_REF_SEL_GOLDEN(golden == last ? VP9_LAST_FRAME :
> +						     VP9_GOLDEN_FRAME);
> +	flags |= VP9_REF_BIAS_GOLDEN(frame->ref_frame_sign_bias &
> +				     V4L2_VP9_SIGN_BIAS_GOLDEN);
> +	flags |= VP9_REF_SEL_ALT(alt != golden ? VP9_ALTREF_FRAME :
> +				 alt != last   ? VP9_GOLDEN_FRAME :
> +						 VP9_LAST_FRAME);

[Severity: Medium]
Is the ternary condition for VP9_REF_SEL_ALT in make_flags1() inverted when
comparing against golden and last?

Because alt != golden is evaluated first and immediately returns
VP9_ALTREF_FRAME when true, the fallback check alt != last is only reached
when alt == golden. When alt == last and golden != last, alt != golden is
true, so this selects VP9_ALTREF_FRAME instead of deduplicating to
VP9_LAST_FRAME.

Should this check alt == last and alt == golden first, such as:

	flags |= VP9_REF_SEL_ALT(alt == last   ? VP9_LAST_FRAME :
				 alt == golden ? VP9_GOLDEN_FRAME :
						 VP9_ALTREF_FRAME);

[ ... ]

> +static int set_tiles(struct avd_ctx *ctx, struct avd_vp9_run *run)
> +{
> +	const struct v4l2_ctrl_vp9_frame *frame = run->decode_params;
> +	struct vb2_v4l2_buffer *src = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx);
> +	const u8 *data = vb2_plane_vaddr(&src->vb2_buf, 0);
> +	unsigned long plane_payload = vb2_get_plane_payload(&src->vb2_buf, 0);
> +	u32 offset =
> +		frame->uncompressed_header_size + frame->compressed_header_size;
> +	u32 num_tile_rows = 1 << frame->tile_rows_log2;
> +	u32 num_tile_cols = 1 << frame->tile_cols_log2;
> +	u32 tile_size, size;
> +	dma_addr_t coded_in;
> +
> +	if (plane_payload < offset)
> +		return -EINVAL;
> +	size = plane_payload - offset;
> +
> +	/* 6.2.6 Compute image size syntax */
> +	u32 sb_64_cols = (((frame->frame_width_minus_1 + 8) >> 3) + 7) >> 3;
> +	u32 sb_64_rows = (((frame->frame_height_minus_1 + 8) >> 3) + 7) >> 3;
> +
> +	for (int row = 0; row < num_tile_rows; row++)
> +		for (int col = 0; col < num_tile_cols; col++) {
> +			if (row == num_tile_rows - 1 &&
> +			    col == num_tile_cols - 1) {
> +				tile_size = size;
> +			} else {
> +				if (size < 4)
> +					return -EINVAL;
> +				tile_size = get_unaligned_be32(&data[offset]);

[Severity: High]
What happens in set_tiles() if vb2_plane_vaddr() returns NULL?

The output queue supports VB2_DMABUF, and vb2_plane_vaddr() can return NULL if
a user-imported DMABUF fails dma_buf_vmap_unlocked() or does not support vmap.
When a frame has more than one tile (num_tile_rows > 1 or num_tile_cols > 1),
get_unaligned_be32(&data[offset]) dereferences NULL + offset.

For comparison, avd_h264_run() in drivers/media/platform/apple/avd/avd-h264.c
explicitly checks the return value of vb2_plane_vaddr() for NULL and returns
-EINVAL.

> +				if (tile_size > size - 4)
> +					return -EINVAL;
> +				offset += 4;
> +				size -= 4;
> +			}
> +
> +			coded_in = run->base.coded_in + offset;
> +			push(AVD_OP_CODED_DATA | AVD_OP_CODED_IN_HI(coded_in),
> +			     "cm3_cmd_set_slice_data");
> +			push(AVD_OP_CODED_IN_LO(coded_in), "coded_in");
> +			push(tile_size, "til_ab8_tile_size");
> +			push(AVD_OP_SL_DIM_START |
> +				     AVD_OP_SL_DIM_START_Y((row * sb_64_rows) /
> +							   num_tile_rows) |
> +				     AVD_OP_SL_DIM_START_X((col * sb_64_cols) /
> +							   num_tile_cols),
> +			     "i");
> +
> +			push(AVD_SL_DIM_END_COL(col) |
> +				     AVD_SL_DIM_END_Y(((row + 1) * sb_64_rows) /
> +							      num_tile_rows - 1) |
> +				     AVD_SL_DIM_END_X(((col + 1) * sb_64_cols) /
> +							      num_tile_cols - 1),
> +			     "til_ac0_tile_dims");

[Severity: High]
Can the tile end coordinates underflow in set_tiles() when num_tile_rows >
sb_64_rows or num_tile_cols > sb_64_cols?

validate_vp9_frame() in drivers/media/v4l2-core/v4l2-ctrls-core.c only bounds
tile_cols_log2 <= 6 (num_tile_cols <= 64) and tile_rows_log2 <= 2
(num_tile_rows <= 4), while validate_dec_params() allows resolutions down to
64x64 (sb_64_cols = 1, sb_64_rows = 1). If userspace passes a frame with
num_tile_rows > sb_64_rows or num_tile_cols > sb_64_cols, then for row = 0 or
col = 0 the integer division ((row + 1) * sb_64_rows) / num_tile_rows or
((col + 1) * sb_64_cols) / num_tile_cols evaluates to 0, and subtracting 1
underflows to 0xffffffff (masked to 0xfff in AVD_SL_DIM_END_Y /
AVD_SL_DIM_END_X).

Also, in drivers/media/platform/apple/avd/avd-inst.h:

#define AVD_SL_DIM_END_COL(v)		FIELD_PREP(GENMASK(27, 24), v)

AVD_SL_DIM_END_COL() is a 4-bit field (max 15), whereas tile_cols_log2 can be
up to 6 (col up to 63). Does col get truncated when tile_cols_log2 >= 5?

> +
> +			offset += tile_size;
> +			size -= tile_size;
> +			avd_end_segment(ctx, true);
> +		}
> +
> +	return 0;
> +}

[ ... ]

> +static int validate_dec_params(struct avd_ctx *ctx,
> +			       const struct v4l2_ctrl_vp9_frame *dec_params)
> +{
> +	unsigned int aligned_width, aligned_height;
> +
> +	if (dec_params->bit_depth > 10)
> +		/* not implemented */
> +		return -EINVAL;
> +
> +	if (dec_params->profile == 1 || dec_params->profile > 2)
> +		return -EINVAL;
> +
> +	if (dec_params->frame_height_minus_1 + 1 < 64 ||
> +	    dec_params->frame_width_minus_1 + 1 < 64)
> +		return -EINVAL;
> +
> +	aligned_width = round_up(dec_params->frame_width_minus_1 + 1, 64);
> +	aligned_height = round_up(dec_params->frame_height_minus_1 + 1, 16);
> +
> +	/*
> +	 * Userspace should update the capture/decoded format when the
> +	 * resolution changes.
> +	 */
> +	if (aligned_width != ctx->decoded_fmt.fmt.pix_mp.width ||
> +	    aligned_height != ctx->decoded_fmt.fmt.pix_mp.height) {
> +		dev_err(ctx->dev->dev,
> +			"unexpected bitstream resolution %dx%d\n",
> +			aligned_width, aligned_height);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int avd_vp9_alloc_bufs(struct avd_ctx *ctx)
> +{
> +	struct avd_dev *avd = ctx->dev;
> +	struct avd_vp9_ctx *vp9_ctx = ctx->priv;
> +	int ret, w, h, bit_depth;
> +
> +	w = fmt_width(ctx);
> +	h = fmt_height(ctx);
> +	bit_depth = (ctx->image_fmt == AVD_IMG_FMT_420_10BIT ||
> +		     ctx->image_fmt == AVD_IMG_FMT_422_10BIT) ?
> +			    10 :
> +			    8;

[Severity: High]
Can the hardware overflow the internal DMA scratch buffers allocated in
avd_vp9_alloc_bufs() if the decoded format or frame bit_depth exceeds the
values present when OUTPUT streaming started?

avd_vp9_alloc_bufs() is only called once from avd_vp9_start() during
VIDIOC_STREAMON on the OUTPUT queue. It sizes the internal DMA buffers
(color, ip_above, lf_above, seg, lf_left, lf_left_info, az_left, above_info)
using fmt_width(ctx) and fmt_height(ctx) (which read ctx->coded_fmt) and
ctx->image_fmt.

However:
1. avd_try_capture_fmt() allows ctx->decoded_fmt to be configured larger than
ctx->coded_fmt, and mid-stream resolution changes update ctx->decoded_fmt
while the OUTPUT queue remains streaming.
2. If VIDIOC_STREAMON(OUTPUT) is called before V4L2_CID_STATELESS_VP9_FRAME is
set, ctx->image_fmt is still AVD_IMG_FMT_ANY, so avd_vp9_alloc_bufs() sizes
the scratch buffers for bit_depth = 8 even if 10-bit frames are subsequently
submitted.
3. validate_dec_params() only checks aligned_width and aligned_height against
ctx->decoded_fmt (not ctx->coded_fmt), and only checks dec_params->bit_depth
<= 10 without verifying that it matches the allocated scratch buffer bit_depth
or capture pixel format.

When set_header() programs the hardware with frame->frame_width_minus_1,
frame->frame_height_minus_1, and frame->bit_depth, won't the decoder DMA past
the end of these scratch buffers?

[ ... ]

> +static int avd_vp9_run(struct avd_ctx *ctx)
> +{
> +	struct avd_vp9_run run;
> +	struct avd_vp9_ctx *vp9_ctx;
> +	struct avd_decoded_buffer *dst;
> +	int ret;
> +
> +	ret = avd_vp9_run_preamble(ctx, &run);
> +	if (ret)
> +		goto postamble;
> +
> +	ret = avd_init_job(
> +		ctx, AVD_CODEC_VP9,
> +		(1 << run.decode_params->tile_rows_log2) *
> +				(1 << run.decode_params->tile_cols_log2) +
> +			1);
> +	if (ret)
> +		goto postamble;
> +
> +	init_probs(ctx, &run);
> +
> +	vp9_ctx = ctx->priv;
> +	dst = vb2_to_avd_decoded_buf(&run.base.bufs.dst->vb2_buf);
> +	update_dec_buf_info(dst, run.decode_params);

[ ... ]

> +static int avd_vp9_start(struct avd_ctx *ctx)
> +{
> +	struct avd_vp9_ctx *vp9_ctx;
> +	int ret;
> +
> +	vp9_ctx = kzalloc_obj(*vp9_ctx, GFP_KERNEL);
> +	if (!vp9_ctx)
> +		return -ENOMEM;
> +
> +	ctx->priv = vp9_ctx;
> +	ret = avd_vp9_alloc_bufs(ctx);
> +	if (ret)
> +		goto err_free_ctx;
> +
> +	avd_init_v4l2_vp9_count_tbl(ctx);
> +
> +	return 0;
> +
> +err_free_ctx:
> +	avd_vp9_stop(ctx);
> +	ctx->priv = NULL;
> +	return ret;
> +}

[ ... ]

---
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-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261020-avd-v3-0-85cbaa2125d8@icloud.com?part=8