In the Linux kernel, the following vulnerability has been resolved:
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.
