CVE-2026-89882: media: rkvdec: hevc: guard INTER_REF_PIC_SET_PRED index underflow
In the Linux kernel, the following vulnerability has been resolved:
media: rkvdec: hevc: guard INTERREFPICSETPRED index underflow
strefpicsetprediction() computes the reference RPS index as strpsidx - (deltaidxminus1 + 1) per HEVC spec equation 7-59. Both operands are u8, so when deltaidxminus1 + 1 exceeds the current index the subtraction wraps and the subsequent array access at calculatedrpsstsets[refrpsidx] reads far out of bounds.
A userspace V4L2 client that can open the RKVDEC m2m decoder can submit an EXTSPSSTRPS control with INTERREFPICSETPRED set and deltaidxminus1 crafted to trigger the underflow.
Reject the entry early when the reference index would underflow.
Affected Software
Event History
Frequently Asked Questions
Who can trigger this issue?
A userspace V4L2 client that can open the RKVDEC mem-to-mem decoder can trigger it. Systems without access to that decoder are not described as exposed.
What input is required to reach the vulnerable path?
The client must submit an EXT_SPS_ST_RPS control with INTER_REF_PIC_SET_PRED set and a crafted delta_idx_minus1 value that makes the calculated reference RPS index underflow.
What does the fix do?
The fix rejects the entry early when the calculated reference index would underflow, preventing the subsequent out-of-bounds access to the calculated RPS array.