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CVE-2026-90162NVD
Vulnerability Summary
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: defer publishing granted locks to prevent UAF/double-free race
In smb2_lock(), mid-batch granted locks are published to connection-wide
(conn->lock_list) and file-wide (fp->lock_list) lists immediately upon
vfs_lock_file() success, while also remaining tracked on the stack-local
rollback_list.
If a subsequent element in the same SMB2_LOCK request array fails
validation or execution, the thread jumps to out: and walks
rollback_list to undo previously granted locks. However, because the
granted lock was already published to conn->lock_list, a concurrent
UNLOCK request on the same connection can find the lock object and
kfree() it before the rollback loop executes.
When the granting thread subsequently walks rollback_list, it
dereferences and frees the already-freed ksmbd_lock structure, resulting
in a Use-After-Free and Double-Free (on both ksmbd_lock and struct
file_lock).
Fix this by deferring the publication of granted locks to
conn->lock_list and fp->lock_list until after the entire array of lock
elements has been processed without error. Mid-batch grants remain
tracked exclusively on the request-local rollback_list until the whole
batch succeeds, eliminating the race window.
ksmbd: defer publishing granted locks to prevent UAF/double-free race
In smb2_lock(), mid-batch granted locks are published to connection-wide
(conn->lock_list) and file-wide (fp->lock_list) lists immediately upon
vfs_lock_file() success, while also remaining tracked on the stack-local
rollback_list.
If a subsequent element in the same SMB2_LOCK request array fails
validation or execution, the thread jumps to out: and walks
rollback_list to undo previously granted locks. However, because the
granted lock was already published to conn->lock_list, a concurrent
UNLOCK request on the same connection can find the lock object and
kfree() it before the rollback loop executes.
When the granting thread subsequently walks rollback_list, it
dereferences and frees the already-freed ksmbd_lock structure, resulting
in a Use-After-Free and Double-Free (on both ksmbd_lock and struct
file_lock).
Fix this by deferring the publication of granted locks to
conn->lock_list and fp->lock_list until after the entire array of lock
elements has been processed without error. Mid-batch grants remain
tracked exclusively on the request-local rollback_list until the whole
batch succeeds, eliminating the race window.
CVSS v3.1 Base Metrics — Score 8.8 (HIGH)
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredLow
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
Affected & Patched Versions
- Linux Linux >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and < a1d26dfb32919088e3638dca01068df3c4507433
- Linux Linux >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and < 29f74f0f2e6df3b393b7b66e810136d0c64e3c59
- Linux Linux >= 5.15
- Linux Linux a1d26dfb32919088e3638dca01068df3c4507433
- Linux Linux 29f74f0f2e6df3b393b7b66e810136d0c64e3c59