CVE-2026-23189 ceph: fix NULL pointer dereference in ceph_mds_auth_match()

In the Linux kernel, the following vulnerability has been resolved: ceph: fix NULL pointer dereference in cephmdsauthmatch The CephFS kernel client has regression starting from 6.18-rc1. We have issue in cephmdsauthmatch if fsname == NULL: const char fsname = mdsc-fsc-mountoptions-mdsnamespace;...