SCTP: Add scope_id validation for link-local binds

SCTP currently permits users to bind to link-local addresses,
but doesn't verify that the scope id specified at bind matches
the interface that the address is configured on.  It was report
that this can hang a system.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/ipv6.c

@@ -844,6 +844,10 @@ static int sctp_inet6_bind_verify(struct sctp_sock *opt, union sctp_addr *addr)
 			dev = dev_get_by_index(addr->v6.sin6_scope_id);
 			if (!dev)
 				return 0;
+			if (!ipv6_chk_addr(&addr->v6.sin6_addr, dev, 0)) {
+				dev_put(dev);
+				return 0;
+			}
 			dev_put(dev);
 		}
 		af = opt->pf->af;