[PATCH v3 4/9] media: rkvdec: bound HEVC tile loops and PPS id to the array capacity

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

compute_tiles_uniform() and compute_tiles_non_uniform() loop over
num_tile_columns_minus1 + 1 / num_tile_rows_minus1 + 1 entries, and
assemble_hw_pps() writes one COLUMN_WIDTH / ROW_HEIGHT register per tile
and indexes priv_tbl->param_set[] by pic_parameter_set_id, all taken from
the untrusted PPS. Use the bounded v4l2_hevc_pps_num_tile_columns() /
v4l2_hevc_pps_num_tile_rows() helpers for the tile loops, and bail out of
assemble_hw_pps() before indexing priv_tbl->param_set[] with an
out-of-range pic_parameter_set_id, so the writes stay within the hardware
tables.

Fixes: 3595375c2301 ("media: rkvdec: Add HEVC backend")
Fixes: c9a59dc2acc7 ("media: rkvdec: Add HEVC support for the VDPU381 variant")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
---
 .../platform/rockchip/rkvdec/rkvdec-hevc-common.c  | 14 ++++++++++----
 .../media/platform/rockchip/rkvdec/rkvdec-hevc.c   |  7 +++++--
 .../platform/rockchip/rkvdec/rkvdec-vdpu381-hevc.c |  2 ++
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c
index 3119f3bc9f98b..753aef3aee51e 100644
--- a/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c
+++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c
@@ -16,6 +16,7 @@
  */
 
 #include <linux/v4l2-common.h>
+#include <media/v4l2-hevc.h>
 #include <media/v4l2-mem2mem.h>
 
 #include "rkvdec.h"
@@ -37,15 +38,17 @@ void compute_tiles_uniform(struct rkvdec_hevc_run *run, u16 log2_min_cb_size,
 			   s32 pic_in_cts_height, u16 *column_width, u16 *row_height)
 {
 	const struct v4l2_ctrl_hevc_pps *pps = run->pps;
+	unsigned int num_cols = v4l2_hevc_pps_num_tile_columns(pps);
+	unsigned int num_rows = v4l2_hevc_pps_num_tile_rows(pps);
 	int i;
 
-	for (i = 0; i < pps->num_tile_columns_minus1 + 1; i++)
+	for (i = 0; i < num_cols; i++)
 		column_width[i] = ((i + 1) * pic_in_cts_width) /
 				  (pps->num_tile_columns_minus1 + 1) -
 				  (i * pic_in_cts_width) /
 				  (pps->num_tile_columns_minus1 + 1);
 
-	for (i = 0; i < pps->num_tile_rows_minus1 + 1; i++)
+	for (i = 0; i < num_rows; i++)
 		row_height[i] = ((i + 1) * pic_in_cts_height) /
 				(pps->num_tile_rows_minus1 + 1) -
 				(i * pic_in_cts_height) /
@@ -57,17 +60,20 @@ void compute_tiles_non_uniform(struct rkvdec_hevc_run *run, u16 log2_min_cb_size
 			       s32 pic_in_cts_height, u16 *column_width, u16 *row_height)
 {
 	const struct v4l2_ctrl_hevc_pps *pps = run->pps;
+	unsigned int num_cols = v4l2_hevc_pps_num_tile_columns(pps);
+	unsigned int num_rows = v4l2_hevc_pps_num_tile_rows(pps);
 	s32 sum = 0;
 	int i;
 
-	for (i = 0; i < pps->num_tile_columns_minus1; i++) {
+	/* The last tile entry is written after the loop, so iterate one less. */
+	for (i = 0; i < num_cols - 1; i++) {
 		column_width[i] = pps->column_width_minus1[i] + 1;
 		sum += column_width[i];
 	}
 	column_width[i] = pic_in_cts_width - sum;
 
 	sum = 0;
-	for (i = 0; i < pps->num_tile_rows_minus1; i++) {
+	for (i = 0; i < num_rows - 1; i++) {
 		row_height[i] = pps->row_height_minus1[i] + 1;
 		sum += row_height[i];
 	}
diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc.c
index ac8b825d080a2..568746dae9a61 100644
--- a/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc.c
+++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc.c
@@ -12,6 +12,7 @@
  *	Jeffy Chen <jeffy.chen@rock-chips.com>
  */
 
+#include <media/v4l2-hevc.h>
 #include <media/v4l2-mem2mem.h>
 
 #include "rkvdec.h"
@@ -156,6 +157,8 @@ static void assemble_hw_pps(struct rkvdec_ctx *ctx,
 	 * packet unit). so the driver copy SPS/PPS information to the exact PPS
 	 * packet unit for HW accessing.
 	 */
+	if (pps->pic_parameter_set_id >= ARRAY_SIZE(priv_tbl->param_set))
+		return;
 	hw_ps = &priv_tbl->param_set[pps->pic_parameter_set_id];
 	memset(hw_ps, 0, sizeof(*hw_ps));
 
@@ -274,9 +277,9 @@ static void assemble_hw_pps(struct rkvdec_ctx *ctx,
 
 	if (pps->flags & V4L2_HEVC_PPS_FLAG_TILES_ENABLED) {
 		/* Userspace also provide column width and row height for uniform spacing */
-		for (i = 0; i <= pps->num_tile_columns_minus1; i++)
+		for (i = 0; i < v4l2_hevc_pps_num_tile_columns(pps); i++)
 			WRITE_PPS(pps->column_width_minus1[i], COLUMN_WIDTH(i));
-		for (i = 0; i <= pps->num_tile_rows_minus1; i++)
+		for (i = 0; i < v4l2_hevc_pps_num_tile_rows(pps); i++)
 			WRITE_PPS(pps->row_height_minus1[i], ROW_HEIGHT(i));
 	} else {
 		WRITE_PPS(((sps->pic_width_in_luma_samples + ctb_size_y - 1) / ctb_size_y) - 1,
diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-vdpu381-hevc.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-vdpu381-hevc.c
index fe6414a175510..6dafa1dd28507 100644
--- a/drivers/media/platform/rockchip/rkvdec/rkvdec-vdpu381-hevc.c
+++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-vdpu381-hevc.c
@@ -145,6 +145,8 @@ static void assemble_hw_pps(struct rkvdec_ctx *ctx,
 	 * packet unit). so the driver copy SPS/PPS information to the exact PPS
 	 * packet unit for HW accessing.
 	 */
+	if (pps->pic_parameter_set_id >= ARRAY_SIZE(priv_tbl->param_set))
+		return;
 	hw_ps = &priv_tbl->param_set[pps->pic_parameter_set_id];
 	memset(hw_ps, 0, sizeof(*hw_ps));
 
-- 
2.53.0