sock_diag: align nlattr properly when needed

I also fix the value of INET_DIAG_MAX. It's wrong since commit 8f840e47f190
which is only in net-next right now, thus I didn't make a separate patch.

Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/sctp_diag.c b/net/sctp/sctp_diag.c
index bb2d8d9..84829ff 100644
--- a/net/sctp/sctp_diag.c
+++ b/net/sctp/sctp_diag.c
@@ -161,8 +161,9 @@
 	if (ext & (1 << (INET_DIAG_INFO - 1))) {
 		struct nlattr *attr;
 
-		attr = nla_reserve(skb, INET_DIAG_INFO,
-				   sizeof(struct sctp_info));
+		attr = nla_reserve_64bit(skb, INET_DIAG_INFO,
+					 sizeof(struct sctp_info),
+					 INET_DIAG_PAD);
 		if (!attr)
 			goto errout;