In the Linux kernel, the following vulnerability has been resolved:
media: v4l2-ctrls: validate HEVC active reference counts
HEVC slice parameters are shared stateless V4L2 controls, but the common validation path does not verify the active L0/L1 reference counts before driver-specific code consumes them.
The original report came from Cedrus, but the active count bounds are not Cedrus-specific. Validate them in the common HEVC slice control path so stateless HEVC drivers get the same basic guarantees as soon as the control is queued.
Do not reject ref_idx_l0/ref_idx_l1 entries here. Existing userspace may use out-of-range sentinel values such as 0xff for missing references, and some hardware can use that information for concealment. Keep this common check limited to the active reference counts.
References
- https://git.kernel.org/stable/c/3068ab802fc98b121dcb451e1f7f4d338ffc7a19
- https://git.kernel.org/stable/c/9a998cc1c348769262d433acb7d238c5fac4b2e0
- https://git.kernel.org/stable/c/afbe4bc252d90a6f8fad869b06d5430f615f22f9
- https://git.kernel.org/stable/c/b01df98a6669d2b67d8aed816021b327fd905998
- https://git.kernel.org/stable/c/dbaf0e0023e2f9332c5164822def7f80b7d2c5ef