[SCTP]: Clean up stale data during association restart

During association restart we may have stale data sitting
on the ULP queue waiting for ordering or reassembly.  This
data may cause severe problems if not cleaned up.  In particular
stale data pending ordering may cause problems with receive
window exhaustion if our peer has decided to restart the
association.
Signed-off-by: NVlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: NSridhar Samudrala <sri@us.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/sctp/ulpqueue.h

@@ -59,6 +59,7 @@ struct sctp_ulpq {
 /* Prototypes. */
 struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *,
 				 struct sctp_association *);
+void sctp_ulpq_flush(struct sctp_ulpq *ulpq);
 void sctp_ulpq_free(struct sctp_ulpq *);
 
 /* Add a new DATA chunk for processing. */

net/sctp/associola.c

@@ -1063,6 +1063,12 @@ void sctp_assoc_update(struct sctp_association *asoc,
 		 */
 		sctp_ssnmap_clear(asoc->ssnmap);
 
+		/* Flush the ULP reassembly and ordered queue.
+		 * Any data there will now be stale and will
+		 * cause problems.
+		 */
+		sctp_ulpq_flush(&asoc->ulpq);
+
 	} else {
 		/* Add any peer addresses from the new association. */
 		list_for_each(pos, &new->peer.transport_addr_list) {

net/sctp/ulpqueue.c

@@ -73,7 +73,7 @@ struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq,
 
 
 /* Flush the reassembly and ordering queues.  */
-static void sctp_ulpq_flush(struct sctp_ulpq *ulpq)
+void sctp_ulpq_flush(struct sctp_ulpq *ulpq)
 {
 	struct sk_buff *skb;
 	struct sctp_ulpevent *event;