[SCTP]: Verify some mandatory parameters.

Verify init_tag and a_rwnd mandatory parameters in INIT and
INIT-ACK chunks.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index ea0f8fa..0b1ddb1 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1775,7 +1775,9 @@
 
 	/* Verify stream values are non-zero. */
 	if ((0 == peer_init->init_hdr.num_outbound_streams) ||
-	    (0 == peer_init->init_hdr.num_inbound_streams)) {
+	    (0 == peer_init->init_hdr.num_inbound_streams) ||
+	    (0 == peer_init->init_hdr.init_tag) ||
+	    (SCTP_DEFAULT_MINWINDOW > ntohl(peer_init->init_hdr.a_rwnd))) {
 
 		sctp_process_inv_mandatory(asoc, chunk, errp);
 		return 0;