sctp: use SCTP_FUTURE_ASSOC for SCTP_RTOINFO sockopt

Check with SCTP_FUTURE_ASSOC instead in
sctp_set/getsockopt_rtoinfo, it's compatible with 0.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/socket.c

@@ -3145,7 +3145,8 @@ static int sctp_setsockopt_rtoinfo(struct sock *sk, char __user *optval, unsigne
 	asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);
 
 	/* Set the values to the specific association */
-	if (!asoc && rtoinfo.srto_assoc_id && sctp_style(sk, UDP))
+	if (!asoc && rtoinfo.srto_assoc_id != SCTP_FUTURE_ASSOC &&
+	    sctp_style(sk, UDP))
 		return -EINVAL;
 
 	rto_max = rtoinfo.srto_max;
@@ -6298,7 +6299,8 @@ static int sctp_getsockopt_rtoinfo(struct sock *sk, int len,
 
 	asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);
 
-	if (!asoc && rtoinfo.srto_assoc_id && sctp_style(sk, UDP))
+	if (!asoc && rtoinfo.srto_assoc_id != SCTP_FUTURE_ASSOC &&
+	    sctp_style(sk, UDP))
 		return -EINVAL;
 
 	/* Values corresponding to the specific association. */