CVE-2026-89990 ceph: lock mutex in ceph_mds_check_access()

In the Linux kernel, the following vulnerability has been resolved: ceph: lock mutex in cephmdscheckaccess MDS session OPEN handling replaces mdsc-scapauths under mdsc-mutex, freeing the previous array and its strings. cephmdscheckaccess traverses this array without holding the mutex. A concurren...