smb3: missing lock when picking channel

jira LE-4669
cve CVE-2024-35999
Rebuild_History Non-Buildable kernel-4.18.0-553.82.1.el8_10
commit-author Steve French <stfrench@microsoft.com>
commit 8094a60

Coverity spotted a place where we should have been holding the
channel lock when accessing the ses channel index.

Addresses-Coverity: 1582039 ("Data race condition (MISSING_LOCK)")
	Cc: stable@vger.kernel.org
	Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
	Signed-off-by: Steve French <stfrench@microsoft.com>
(cherry picked from commit 8094a60)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

fs/cifs/transport.c

@@ -1058,9 +1058,11 @@ struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
 		if (CIFS_CHAN_NEEDS_RECONNECT(ses, index))
 			goto pick_another;
 	}
+
+	server = ses->chans[index].server;
 	spin_unlock(&ses->chan_lock);
 
-	return ses->chans[index].server;
+	return server;
 }
 
 int