CVE-2026-80926

Critical

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in oplock break notification smb2_oplock_break_noti() reads opinfo->conn without any lock and dereferences it after two allocations which may sleep. When the durable handle owning the oplock is disconnected, session_fd_check() clears opinfo->conn and drops its conn reference under ci->m_lock, and the last ksmbd_conn_put() frees the connection. A break triggered by another connection that races with the teardown can then resurrect the freed connection: ksmbd_conn_get() is a plain atomic_inc, and the queued break work later dereferences the stale conn via ksmbd_conn_write(), a use-after-free reachable by any authenticated client holding a durable batch oplock. Thread the caller's inode into the notification path instead of taking a new reference on it. Every caller of oplock_break() already holds a live ksmbd_file (or an explicit ksmbd_inode_lookup_lock() reference, in the parent lease break paths) on the inode that owns the break target's oplock list, so ci cannot be freed during the call, and its lock can be taken without dereferencing opinfo->o_fp, which a concurrent close may free. Select and pin the connection under ci->m_lock, the same lock session_fd_check() and ksmbd_reopen_durable_fd() use to update opinfo->conn, so a concurrent detach either loses the race to the clear or keeps the connection alive until the notification work releases it. Transfer the reference to the work item and release it on allocation failures.

SeverityCritical
CVSS9.8
Exploit probability—
ProductLinux
PublishedSep 11, 2026
First seenSep 11, 2026

How to fix

Update
  • Linux Linux892f643b141aee3f7aa7c0fc61ddcb55c59f1996, 5de0527f782430b1109a447646e32033ad018a6a, c8279ae8df68cce9cd3b785e85f7a86c80a46e78, 8cc98db4fc590e6c7d9db6529320982ee16c5d1d, 0e753899627b5e28a9fea8bca98262a6f65a2452, 6.6.158, 6.12.111, 6.18.51, 7.1 or later

Affected products

ProductAffected versionsFixed in
Linux Linux945a86b21b40fb17183f5b27461baa6f03e2467f ≤ v < 892f643b141aee3f7aa7c0fc61ddcb55c59f1996, 1ff58dcfcab434ebb51649da33774fbb8e1f7b67 ≤ v < 5de0527f782430b1109a447646e32033ad018a6a, e735dbd489e3ea02be78dba991056fe1138be51e ≤ v < c8279ae8df68cce9cd3b785e85f7a86c80a46e78, b003086d76968298f22e7cf62239833b5a3a06b1 ≤ v < 8cc98db4fc590e6c7d9db6529320982ee16c5d1d, b003086d76968298f22e7cf62239833b5a3a06b1 ≤ v < 0e753899627b5e28a9fea8bca98262a6f65a2452, 75e33deda658c1ab3a9336cbdb1436536f9b3660, 6.6.143 ≤ v < 6.6.158, 6.12.94 ≤ v < 6.12.111, 6.18.36 ≤ v < 6.18.51, 7.0.13 ≤ v < 7.1, 7.1892f643b141aee3f7aa7c0fc61ddcb55c59f1996, 5de0527f782430b1109a447646e32033ad018a6a, c8279ae8df68cce9cd3b785e85f7a86c80a46e78, 8cc98db4fc590e6c7d9db6529320982ee16c5d1d, 0e753899627b5e28a9fea8bca98262a6f65a2452, 6.6.158, 6.12.111, 6.18.51, 7.1

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