CVE-2026-80548s390/vfio_ccw: Selectively expand io_mutex

Official 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0
• https://git.kernel.org/stable/c/56d7488533ceac4e986e96e15c9e487a2245bc01
• https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc
• https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd
• https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e
• https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8
• https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a