[PATCH 4.15 02/53] netfilter: ipset: Missing nfnl_lock()/nfnl_unlock() is added to ip_set_net_exit()

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxxxxxx>

commit f998b6b10144cd9809da6af02758615f789e8aa1 upstream.

Patch "netfilter: ipset: use nfnl_mutex_is_locked" is added the real
mutex locking check, which revealed the missing locking in ip_set_net_exit().

Signed-off-by: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxxxxxx>
Reported-by: syzbot+36b06f219f2439fe62e1@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/netfilter/ipset/ip_set_core.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -2055,6 +2055,7 @@ ip_set_net_exit(struct net *net)
 
 	inst->is_deleted = true; /* flag for ip_set_nfnl_put */
 
+	nfnl_lock(NFNL_SUBSYS_IPSET);
 	for (i = 0; i < inst->ip_set_max; i++) {
 		set = ip_set(inst, i);
 		if (set) {
@@ -2062,6 +2063,7 @@ ip_set_net_exit(struct net *net)
 			ip_set_destroy_set(set);
 		}
 	}
+	nfnl_unlock(NFNL_SUBSYS_IPSET);
 	kfree(rcu_dereference_protected(inst->ip_set_list, 1));
 }