net: bridge: fix a possible memory leak in __vlan_add

After per-port vlan stats, vlan stats should be released
when fail to add vlan

Fixes: 9163a0fc ("net: bridge: add support for per-port vlan stats")
CC: bridge@lists.linux-foundation.org
cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
CC: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_vlan.c

@@ -303,6 +303,10 @@ static int __vlan_add(struct net_bridge_vlan *v, u16 flags)
 	if (p) {
 		__vlan_vid_del(dev, br, v->vid);
 		if (masterv) {
+			if (v->stats && masterv->stats != v->stats)
+				free_percpu(v->stats);
+			v->stats = NULL;
+
 			br_vlan_put_master(masterv);
 			v->brvlan = NULL;
 		}