CVE-2026-89652

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

ceph: bound copied dentry name length in NFS export get_name

cephgetname() copies the MDS-supplied name into the caller's

NAMEMAX-sized buffer with memcpy(name, rinfo->dname, rinfo->dnamelen)

and then writes name[rinfo->dnamelen] = 0, without checking dnamelen

against NAME_MAX. A malicious or buggy MDS that returns a LOOKUPNAME reply

with dnamelen > NAMEMAX overflows the buffer. _getsnap_name() copies

rde->name / rde->name_len the same unchecked way.

Impact: a malicious or compromised Ceph MDS overflows the NAME_MAX name

buffer in a client's NFS-export get_name path, a slab out-of-bounds write

reported by KASAN. Reachable when a CephFS mount is re-exported over NFS.

Add cephexportcopyname(), which rejects lengths above NAMEMAX with

-ENAMETOOLONG before the copy, and use it in both cephgetname() and

_getsnap_name().