From 052c5ed5a1d96a6b24fd50ccda16fc6841ee7ca3 Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Wed, 27 May 2026 15:47:37 -0400 Subject: [PATCH] media: rkvdec: hevc: guard INTER_REF_PIC_SET_PRED index underflow st_ref_pic_set_prediction() computes the reference RPS index as st_rps_idx - (delta_idx_minus1 + 1) per HEVC spec equation 7-59. Both operands are u8, so when delta_idx_minus1 + 1 exceeds the current index the subtraction wraps and the subsequent array access at calculated_rps_st_sets[ref_rps_idx] reads far out of bounds. A userspace V4L2 client that can open the RKVDEC m2m decoder can submit an EXT_SPS_ST_RPS control with INTER_REF_PIC_SET_PRED set and delta_idx_minus1 crafted to trigger the underflow. Reject the entry early when the reference index would underflow. Fixes: c9a59dc2acc7 ("media: rkvdec: Add HEVC support for the VDPU381 variant") Cc: stable@vger.kernel.org Suggested-by: Detlev Casanova Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Reviewed-by: Nicolas Dufresne Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil --- drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c index f89602075121..9c4a6093af32 100644 --- a/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c @@ -209,6 +209,9 @@ static void st_ref_pic_set_prediction(struct rkvdec_hevc_run *run, int idx, int i, j; int dPoc; + if ((unsigned int)rps_data->delta_idx_minus1 + 1 > idx) + return; + ref_rps_idx = st_rps_idx - (rps_data->delta_idx_minus1 + 1); /* 7-59 */ delta_rps = (1 - 2 * rps_data->delta_rps_sign) * (rps_data->abs_delta_rps_minus1 + 1); /* 7-60 */