ksmbd: fix use-after-free in oplock break notification

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80926
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:18:56 UTC
Updated2026-09-21 14:17:21 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.004500000 probability, percentile 0.384810000 (date 2026-09-22)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1ff58dcfcab434ebb51649da33774fbb8e1f7b67 5de0527f782430b1109a447646e32033ad018a6a git Not specified
CNA Linux Linux affected e735dbd489e3ea02be78dba991056fe1138be51e c8279ae8df68cce9cd3b785e85f7a86c80a46e78 git Not specified
CNA Linux Linux affected b003086d76968298f22e7cf62239833b5a3a06b1 8cc98db4fc590e6c7d9db6529320982ee16c5d1d git Not specified
CNA Linux Linux affected b003086d76968298f22e7cf62239833b5a3a06b1 0e753899627b5e28a9fea8bca98262a6f65a2452 git Not specified
CNA Linux Linux affected 945a86b21b40fb17183f5b27461baa6f03e2467f git Not specified
CNA Linux Linux affected 75e33deda658c1ab3a9336cbdb1436536f9b3660 git Not specified
CNA Linux Linux affected 6.12.94 6.12.111 semver Not specified
CNA Linux Linux affected 6.18.36 6.18.51 semver Not specified
CNA Linux Linux affected 6.6.143 6.7 semver Not specified
CNA Linux Linux affected 7.0.13 7.1 semver Not specified
CNA Linux Linux affected 7.1 Not specified
CNA Linux Linux unaffected 7.1 semver Not specified
CNA Linux Linux unaffected 6.12.111 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.5 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8cc98db4fc590e6c7d9db6529320982ee16c5d1d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c8279ae8df68cce9cd3b785e85f7a86c80a46e78 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5de0527f782430b1109a447646e32033ad018a6a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0e753899627b5e28a9fea8bca98262a6f65a2452 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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