[NETFILTER]: Fix unbalanced read_unlock_bh in ctnetlink

NFA_NEST calls NFA_PUT which jumps to nfattr_failure if the skb has no
room left. We call read_unlock_bh at nfattr_failure for the NFA_PUT inside
the locked section, so move NFA_NEST inside the locked section too.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_conntrack_proto_tcp.c

@@ -341,9 +341,10 @@ static int tcp_print_conntrack(struct seq_file *s,
 static int tcp_to_nfattr(struct sk_buff *skb, struct nfattr *nfa,
 			 const struct ip_conntrack *ct)
 {
-	struct nfattr *nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
+	struct nfattr *nest_parms;
 
 	read_lock_bh(&tcp_lock);
+	nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
 	NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t),
 		&ct->proto.tcp.state);
 	read_unlock_bh(&tcp_lock);