security: Fix for CVE-2020-1763

pluto will crash on a null pointer dereference when trying to log an error
for an IKEv1 packet containing bogus information and/or flags.

Signed-off-by: Paul Wouters <pwouters@redhat.com>

programs/pluto/ikev1.c

@@ -2129,7 +2129,7 @@ void process_packet_tail(struct msg_digest *md)
 						"%smessage ignored because it contains a payload type (%s) unexpected by state %s",
 						excuse,
 						enum_show(&ikev1_payload_names, np),
-						st->st_state->name);
+						finite_states[smc->state]->name);
 					if (!md->encrypted) {
 						SEND_NOTIFICATION(INVALID_PAYLOAD_TYPE);
 					}