sctp: fix stream update when processing dupcookie

Since commit 3dbcc105 ("sctp: alloc stream info when initializing
asoc"), stream and stream.out info are always alloced when creating
an asoc.

So it's not correct to check !asoc->stream before updating stream
info when processing dupcookie, but would be better to check asoc
state instead.

Fixes: 3dbcc105 ("sctp: alloc stream info when initializing asoc")
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Acked-by: NVlad Yasevich <vyasevich@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/associola.c

@@ -1176,7 +1176,9 @@ void sctp_assoc_update(struct sctp_association *asoc,
 
 		asoc->ctsn_ack_point = asoc->next_tsn - 1;
 		asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
-		if (!asoc->stream) {
+
+		if (sctp_state(asoc, COOKIE_WAIT)) {
+			sctp_stream_free(asoc->stream);
 			asoc->stream = new->stream;
 			new->stream = NULL;
 		}