CVE-2026-53271ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers

Official 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/945a86b21b40fb17183f5b27461baa6f03e2467f
• https://git.kernel.org/stable/c/1ff58dcfcab434ebb51649da33774fbb8e1f7b67
• https://git.kernel.org/stable/c/e735dbd489e3ea02be78dba991056fe1138be51e
• https://git.kernel.org/stable/c/75e33deda658c1ab3a9336cbdb1436536f9b3660
• https://git.kernel.org/stable/c/b003086d76968298f22e7cf62239833b5a3a06b1