CVE-2026-80926

Status: UPDATED  |  Advisory ID: CVE-2026-80926

Key Details

Affected Products, Subsystems & Sectors

What to Know

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. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References