CVE-2026-98897 ksmbd: don't hold ci->m_lock while waiting for a lease break ack
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-98897?
CVE-2026-98897 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: don't hold ci->m_lock while waiting for a lease break ack
When a cifs.ko client caches a read-handle (RH) lease via deferred close and a conflicting open arrives, ksmbd breaks the lease and waits for the acknowledgment in wait_for_break_ack() for up to OPLOCK_WAIT_TIME (35s). __smb_break_all_levII_oplock() runs that wait while holding ci->m_lock for read.
cifs.ko reacts to a handle-lease break by closing the deferred handle rather than sending a lease break acknowledgment. That close path (close_id_del_oplock() -> opinfo_del()) takes ci->m_lock for write and is exactly what would wake the waiter, but it blocks on the read lock held by the waiting thread. The break is then resolved only by the 35s timeout, so xfstests generic/001 takes ~78s with leases enabled versus ~4s with oplocks only.
Collect the target opinfos (each pinned with a reference) while holding ci->m_lock, then break them after releasing it, matching how smb_grant_oplock() already breaks a conflicting lease using only a reference. The reference keeps the opinfo (and its conn and lease) alive across the unlocked window, and a close racing the break is handled by the existing OPLOCK_CLOSING state check. Apply the same fix to the parent lease break paths.
Which versions are affected by CVE-2026-98897?
How do I fix CVE-2026-98897?
Upgrade to a fixed version.
Is CVE-2026-98897 being exploited?
There is no known exploitation of CVE-2026-98897 in the wild and no public exploit code.
Sources
Also known as AZL-110573, BELL-CVE-2026-98897, DEBIAN-CVE-2026-98897, GHSA-83j5-g9m2-9mf4, UBUNTU-CVE-2026-98897.