CVE-2026-80548

/// Technical description

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

s390/vfio_ccw: Selectively expand io_mutex

The io_mutex was defined to serialize the io_regions, but then has

also sort of been associated with the I/O themselves because of

the close relationship they share.

With the handful of races that are possible, the choices are either to:

A) expand the scope of io_mutex to close these remaining windows, or

B) reduce the scope of io_mutex to just io_region, and introduce a new

lock mechanism for the remaining I/O resources

This patch implements A, since B brings with it a lot more interactions

that would need to be tracked and kept in a correct hierarchy. It also

takes advantage of the workqueue element for cp_free() that now gets

called out of fsm_notoper(), which could be invoked out of an interrupt

context and thus cannot acquire a mutex itself.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References