[PATCH v3 7/9] media: verisilicon: rockchip: reject AV1 frames exceeding the tile capacity

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

rockchip_vpu981_av1_dec_set_tile_info() indexes the tile group entry
array by tile1 * tile_cols + tile0, reading up to tile_cols * tile_rows
entries, lays out one descriptor per tile in the AV1_MAX_TILES tile_info
buffer, and programs the real tile_cols / tile_rows into the hardware.

The tile group entry control is a dynamic array sized to the number of
entries userspace submitted, independent of tile_cols / tile_rows, so a
frame that claims more tiles than entries reads past the array. A frame
that claims more than AV1_MAX_TILES tiles also leaves the hardware
programmed for more tiles than the descriptor buffer holds.

Reject both in prepare_run(): tile_cols * tile_rows must not exceed the
submitted entry count or AV1_MAX_TILES. The entry count is read via
v4l2_ctrl_find() (ctrl->elems). This mirrors the bound the mediatek AV1
decoder already enforces.

Fixes: 727a400686a2 ("media: verisilicon: Add Rockchip AV1 decoder")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
---
 .../verisilicon/rockchip_vpu981_hw_av1_dec.c  | 25 ++++++++++++++++---
 1 file changed, 22 insertions(+), 3 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 fd00dbd79fe46..00aa566a4ccdb 100644
--- a/drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c
+++ b/drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c
@@ -431,20 +431,39 @@ static int rockchip_vpu981_av1_dec_prepare_run(struct hantro_ctx *ctx)
 {
 	struct hantro_av1_dec_hw_ctx *av1_dec = &ctx->av1_dec;
 	struct hantro_av1_dec_ctrls *ctrls = &av1_dec->ctrls;
+	const struct v4l2_av1_tile_info *tile_info;
+	struct v4l2_ctrl *tge;
+	u32 num_tiles;
 
 	ctrls->sequence = hantro_get_ctrl(ctx, V4L2_CID_STATELESS_AV1_SEQUENCE);
 	if (WARN_ON(!ctrls->sequence))
 		return -EINVAL;
 
-	ctrls->tile_group_entry =
-	    hantro_get_ctrl(ctx, V4L2_CID_STATELESS_AV1_TILE_GROUP_ENTRY);
-	if (WARN_ON(!ctrls->tile_group_entry))
+	tge = v4l2_ctrl_find(&ctx->ctrl_handler,
+			     V4L2_CID_STATELESS_AV1_TILE_GROUP_ENTRY);
+	if (WARN_ON(!tge))
 		return -EINVAL;
+	ctrls->tile_group_entry = tge->p_cur.p;
 
 	ctrls->frame = hantro_get_ctrl(ctx, V4L2_CID_STATELESS_AV1_FRAME);
 	if (WARN_ON(!ctrls->frame))
 		return -EINVAL;
 
+	/*
+	 * rockchip_vpu981_av1_dec_set_tile_info() indexes the tile group
+	 * entry array by tile1 * tile_cols + tile0, so it reads up to
+	 * tile_cols * tile_rows entries, and lays out one descriptor per tile
+	 * in the AV1_MAX_TILES tile_info buffer while programming the real
+	 * tile geometry into the hardware. Reject a frame that claims more
+	 * tiles than userspace submitted, or more than the hardware tile
+	 * buffer holds, so the read stays in bounds and the programmed
+	 * geometry matches the descriptors written.
+	 */
+	tile_info = &ctrls->frame->tile_info;
+	num_tiles = (u32)tile_info->tile_cols * tile_info->tile_rows;
+	if (num_tiles > tge->elems || num_tiles > AV1_MAX_TILES)
+		return -EINVAL;
+
 	ctrls->film_grain =
 	    hantro_get_ctrl(ctx, V4L2_CID_STATELESS_AV1_FILM_GRAIN);
 
-- 
2.53.0