CVE-2026-64396

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

ksmbd: fix UAF of struct filelock in SMB2LOCK deferred-lock cancellation

When a blocking byte-range lock request is deferred in the FILELOCKDEFERRED path, ksmbd registers the asynchronous work into the connection's asyncrequests list via setupasyncwork(). The cancel callback smb2removeblockedlock() holds a reference to the flock.

If the lock waiter is subsequently woken up but the work state is no longer KSMBDWORKACTIVE (e.g., due to a concurrent cancellation), the cleanup path calls locksfreelock(flock) without dequeuing the work from the asyncrequests list. Concurrently, smb2cancel() walks the list under conn->request_lock and invokes the cancel callback, which then dereferences the already freed 'flock'. This leads to a slab-use-after-free inside __wakeupcommon.

Fix this by restructuring the cleanup logic after the worker returns from ksmbdvfsposixlockwait(). Move listdel(&smblock->llist) and releaseasyncwork(work) to the top of the cleanup block. This guarantees that the async work is completely dequeued and serialized under conn->requestlock before locksfreelock(flock) is called, rendering the flock unreachable for any concurrent smb2cancel().