Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: x86,fs/resctrl: Prevent out-of-bounds access while offlining CPU when SNC enabled The architecture updates the cpu_mask in a domain's header to track which online CPUs are associated with the domain. When this mask becomes empty the architecture initiates offline of the domain that includes calling on resctrl fs to offline the domain. If it is a monitoring domain in which LLC occupancy is tracked resctrl fs forces the limbo handler to clear all busy RMID state associated with the domain. The limbo handler always reads the current event value associated with a busy RMID irrespective of it being checked as part of regular "is it still busy" check or whether it will be forced released anyway. When reading an RMID on a system with SNC enabled the "logical RMID" is converted to the "physical RMID" and this conversion requires the NUMA node ID of the resctrl monitoring domain that is in turn determined by querying the NUMA node ID of any CPU belonging to the monitoring domain. When the monitoring domain is going offline its cpu_mask is empty causing the NUMA node ID query via cpu_to_node() to be done with "nr_cpu_ids" as argument resulting in an out-of-bounds access. Refactor the limbo handler to skip reading the RMID when the RMID will just be forced to no longer be dirty in the domain anyway. Add a safety check to the architecture's RMID reader to protect against this scenario.
References
- https://git.kernel.org/stable/c/58c5ec23b1a238eb75cb0aba6f69d8f9e68ef0b2
- https://git.kernel.org/stable/c/be1567992417dc92133e74126de7a6066c825ac9
- https://git.kernel.org/stable/c/ebc300b7ee0c669fa76a7a8858298ff32e296103
- https://git.kernel.org/stable/c/fc16126cc11d9f507130bf84ab137ee0938c900e
FAQ
What is CVE-2026-64477?
CVE-2026-64477 is a documented vulnerability. In the Linux kernel, the following vulnerability has been resolved: x86,fs/resctrl: Prevent out-of-bounds access while offlining CPU when SNC enabled The architecture updates the cpu_mask in a domai...
How severe is CVE-2026-64477?
CVSS scoring is not yet available for CVE-2026-64477. Check NVD for updates.
Is there a patch for CVE-2026-64477?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.