ksmbd: reclaim ended sessions on logoff and expiration

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: reclaim ended sessions on logoff and expiration

LOGOFF and previous-session replacement leave sessions Expired with a zero credential expiry. Ended sessions can retain their memory and connection slots when no further setup arrives on the owning connection.

Unpublish a logged-off session while the request reference keeps its response signing and encryption keys alive. Remove its procfs entry before dropping the table reference so a reader cannot remove its own entry on the last put. Clear proc_entry after removal to avoid removing it twice.

Reclaim ended sessions from the global table in the existing expiration worker before it acquires conn_list_lock. Only select Expired sessions with zero credential expiry and no references beyond the table reference. Keep sessions whose Kerberos credentials expired available for reauthentication.

Unlink the session from its setup connection and all channel connections, so SMB2 sessions and sessions with only secondary SMB3 channels are covered. The session already holds connection references, and sessions_table_lock prevents concurrent channel removal. Queue sessions on a separate disposal list, leaving their hash nodes unhashed, and remove procfs entries and drop table references outside the locks.

Keep the pending setup check before allocating a new session so abandoned InProgress sessions can release their slots even at the connection limit. Retain the timeout and reference checks and dispose of those sessions outside the locks. Leave ended Expired sessions to the expiration worker.