This vulnerability in the Linux kernel's resctrl filesystem occurs when offlining a CPU in a monitoring domain with SNC enabled. The cpu_mask that tracks online CPUs becomes empty, causing the domain to be offlined. The limbo handler attempts to read RMID event values regardless, which requires converting logical RMID to physical RMID by querying the NUMA node ID of a CPU in the domain. Since the cpu_mask is empty, the query uses an invalid CPU ID (nr_cpu_ids), resulting in out-of-bounds memory access. The fix involves skipping RMID reads when the domain is offlining and adding safety checks to prevent invalid NUMA node queries.

The vulnerability causes out-of-bounds memory access in the Linux kernel during CPU offlining in resctrl monitoring domains with SNC enabled. This could lead to kernel instability or crashes. No known exploits in the wild have been reported. The impact is limited to systems using the affected resctrl feature with SNC enabled.

A fix has been implemented in the Linux kernel that refactors the limbo handler to avoid reading RMID values when the domain is offlining and adds safety checks to prevent out-of-bounds NUMA node queries. Users should apply the official Linux kernel updates that include this fix. Patch status is not explicitly stated here; check the vendor or Linux kernel advisories for the specific fixed versions and apply updates accordingly.