[IPV6]: Lost locking when inserting a flowlabel in ipv6_fl_list

The new flowlabels should be inserted into the sock list
under the ip6_sk_fl_lock. This was lost in one place.

This list is naturally protected with the socket lock, but
the fl6_sock_lookup() is called without it, so another
protection is required.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/ip6_flowlabel.c

@@ -409,6 +409,16 @@ static int ipv6_opt_cmp(struct ipv6_txoptions *o1, struct ipv6_txoptions *o2)
 	return 0;
 }
 
+static inline void fl_link(struct ipv6_pinfo *np, struct ipv6_fl_socklist *sfl,
+		struct ip6_flowlabel *fl)
+{
+	write_lock_bh(&ip6_sk_fl_lock);
+	sfl->fl = fl;
+	sfl->next = np->ipv6_fl_list;
+	np->ipv6_fl_list = sfl;
+	write_unlock_bh(&ip6_sk_fl_lock);
+}
+
 int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 {
 	int err;
@@ -513,11 +523,7 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 					fl1->linger = fl->linger;
 				if ((long)(fl->expires - fl1->expires) > 0)
 					fl1->expires = fl->expires;
-				write_lock_bh(&ip6_sk_fl_lock);
-				sfl1->fl = fl1;
-				sfl1->next = np->ipv6_fl_list;
-				np->ipv6_fl_list = sfl1;
-				write_unlock_bh(&ip6_sk_fl_lock);
+				fl_link(np, sfl1, fl1);
 				fl_free(fl);
 				return 0;
 
@@ -545,9 +551,7 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 			}
 		}
 
-		sfl1->fl = fl;
-		sfl1->next = np->ipv6_fl_list;
-		np->ipv6_fl_list = sfl1;
+		fl_link(np, sfl1, fl);
 		return 0;
 
 	default: