CVE-2026-64390

Technical Description

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

ksmbd: track the connection owning a byte-range lock

SMB2_LOCK adds each granted byte-range lock to both the file lock list

and the lock list of the connection which handled the request. The

final close and durable handle paths, however, remove the connection

list entry while holding fp->conn->llist_lock.

With SMB3 multichannel, the connection handling the LOCK request can be

different from the connection which opened the file. The entry can

therefore be removed under a different spinlock from the one protecting

the list it belongs to. A concurrent traversal can then access freed

struct ksmbd_lock and struct file_lock objects.

Record the connection owning each lock's clist entry and hold a

reference to it while the entry is linked. Use that connection and its

llist_lock for unlock, rollback, close, and durable preserve. Durable

reconnect assigns the new connection as the owner when publishing the

locks again.

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