l2tp: clean up stale tunnel or session in pppol2tp_connect's error path

pppol2tp_connect() may create a tunnel or a session. Remove them in
case of error.

Fixes: fd558d186d ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_ppp.c

@@ -612,6 +612,8 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 	u32 session_id, peer_session_id;
 	bool drop_refcnt = false;
 	bool drop_tunnel = false;
+	bool new_session = false;
+	bool new_tunnel = false;
 	int ver = 2;
 	int fd;
 
@@ -722,6 +724,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 				goto end;
 			}
 			drop_tunnel = true;
+			new_tunnel = true;
 		}
 	} else {
 		/* Error if we can't find the tunnel */
@@ -788,6 +791,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 			goto end;
 		}
 		drop_refcnt = true;
+		new_session = true;
 	}
 
 	/* Special case: if source & dest session_id == 0x0000, this
@@ -834,6 +838,12 @@ out_no_ppp:
 		  session->name);
 
 end:
+	if (error) {
+		if (new_session)
+			l2tp_session_delete(session);
+		if (new_tunnel)
+			l2tp_tunnel_delete(tunnel);
+	}
 	if (drop_refcnt)
 		l2tp_session_dec_refcount(session);
 	if (drop_tunnel)