CVE-2026-53271
ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers
Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown.
INFO
Published Date :
June 25, 2026, 8:39 a.m.
Last Modified :
June 25, 2026, 8:39 a.m.
Remotely Exploit :
No
Source :
Linux
Affected Products
The following products are affected by CVE-2026-53271
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Apply the Linux kernel patch for ksmbd.
- Ensure opinfo->conn is read with READ_ONCE().
- Add a NULL check for opinfo->conn.
- Return early if opinfo->conn is NULL.
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