CVE-2026-64390: ksmbd: track the connection owning a byte-range lock
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: track the connection owning a byte-range lock
SMB2LOCK 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->llistlock.
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 ksmbdlock and struct filelock 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 llistlock for unlock, rollback, close, and durable preserve. Durable reconnect assigns the new connection as the owner when publishing the locks again.
Affected Software
Remediation
Event History
Frequently Asked Questions
When is this issue most likely to be triggered?
It is associated with SMB3 multichannel, where the connection processing a byte-range lock request differs from the connection that opened the file. Concurrent traversal of the affected lock list can then access freed lock objects.
What level of attacker access is indicated by the severity data?
The CVSS vector indicates network reachability, low attack complexity, no user interaction, and low privileges required. Successful exploitation can affect confidentiality, integrity, and availability.
What should teams do if they cannot immediately apply the patch?
The provided remediation is to apply the available patch. No alternative workaround or configuration-based mitigation is specified in the supplied information.
How can I determine whether my kernel includes the fix?
No affected kernel-version range is provided. Compare your kernel's applied patches or source history with the listed stable commit references to determine whether the remediation has been incorporated.