- When we close a socket with pending assoc's that are still

shutting down, NULL out the socket pointer so we won't
  ever refer to a dead socket.

Obtained from: Neil Wilson

sys/netinet/sctp_pcb.c

@@ -3275,6 +3275,7 @@ sctp_inpcb_free(struct sctp_inpcb *inp, int immediate, int from)
 #ifdef SCTP_LOG_CLOSING
 			sctp_log_closing(inp, NULL, 2);
 #endif
+			inp->sctp_socket = NULL;
 			return;
 		}
 	}