CVE-2026-89443

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

platform/x86: ISST: Validate level in perf mask ioctls

isst_if_get_perf_level_mask() and isst_if_get_base_freq_mask() use the
user-provided level as an index into perf_levels[] via
_read_pp_level_info() and _read_bf_level_info(), but neither helper
validates it first.

The adjacent level-info helpers reject levels above max_level before
reading the same per-level register block. Add the same bounds checks to
the mask helpers, and reject disabled SST-PP levels in
isst_if_get_perf_level_mask() to match isst_if_get_perf_level_info().

This prevents out-of-bounds reads from the per-level offset table on
invalid ioctl input.