[PATCH v3 2/9] media: v4l2-ctrls: validate AV1 tile counts

[Michael Bommarito <michael.bommarito@gmail.com>]

The stateless AV1 decoders use tile_info.tile_cols and tile_rows as loop
bounds and as indices into the mi_*_starts[] and *_in_sbs_minus_1[]
arrays, as the divisor for context_update_tile_id, and their product
bounds the per-tile descriptor buffers, but std_validate_compound() does
not bound these u8 fields. Reject a V4L2_CTRL_TYPE_AV1_FRAME whose
tile_cols or tile_rows exceeds V4L2_AV1_MAX_TILE_COLS / _ROWS, or whose
product exceeds V4L2_AV1_MAX_TILE_COUNT. A zero tile count is left to the
consuming driver so the zero-initialised control that existing userspace
submits is still accepted.

Fixes: 9de30f579980 ("media: Add AV1 uAPI")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
---
 drivers/media/v4l2-core/v4l2-ctrls-core.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c
index 6d478e1a5ef22..fb20ad13dfec7 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-core.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c
@@ -790,10 +790,30 @@ static int validate_av1_film_grain(struct v4l2_ctrl_av1_film_grain *fg)
 	return 0;
 }
 
+static int validate_av1_tile_info(struct v4l2_av1_tile_info *t)
+{
+	/*
+	 * tile_cols and tile_rows index the per-tile descriptor arrays and
+	 * bound the tile loops in the stateless AV1 drivers; the product
+	 * bounds the total tile descriptor count.
+	 */
+	if (t->tile_cols > V4L2_AV1_MAX_TILE_COLS ||
+	    t->tile_rows > V4L2_AV1_MAX_TILE_ROWS)
+		return -EINVAL;
+
+	if ((u32)t->tile_cols * t->tile_rows > V4L2_AV1_MAX_TILE_COUNT)
+		return -EINVAL;
+
+	return 0;
+}
+
 static int validate_av1_frame(struct v4l2_ctrl_av1_frame *f)
 {
 	int ret = 0;
 
+	ret = validate_av1_tile_info(&f->tile_info);
+	if (ret)
+		return ret;
 	ret = validate_av1_quantization(&f->quantization);
 	if (ret)
 		return ret;
-- 
2.53.0