sctp: fix potential reference of a freed pointer

When sctp attempts to update an assocition, it removes any
addresses that were not in the updated INITs.  However, the loop
may attempt to refrence a transport with address after removing it.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/associola.c

@@ -1194,8 +1194,10 @@ void sctp_assoc_update(struct sctp_association *asoc,
 	/* Remove any peer addresses not present in the new association. */
 	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
 		trans = list_entry(pos, struct sctp_transport, transports);
-		if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr))
-			sctp_assoc_del_peer(asoc, &trans->ipaddr);
+		if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
+			sctp_assoc_rm_peer(asoc, trans);
+			continue;
+		}
 
 		if (asoc->state >= SCTP_STATE_ESTABLISHED)
 			sctp_transport_reset(trans);