vxlan: fix a potential issue when create a new vxlan fdb entry.

vxlan_fdb_append may return error, so add the proper check,
otherwise it will cause memory leak.
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>

Changes in v2:
  - Unnecessary to initialize rc to zero.
Acked-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -611,6 +611,7 @@ static int vxlan_fdb_create(struct vxlan_dev *vxlan,
 	struct vxlan_rdst *rd = NULL;
 	struct vxlan_fdb *f;
 	int notify = 0;
+	int rc;
 
 	f = __vxlan_find_mac(vxlan, mac);
 	if (f) {
@@ -641,8 +642,7 @@ static int vxlan_fdb_create(struct vxlan_dev *vxlan,
 		if ((flags & NLM_F_APPEND) &&
 		    (is_multicast_ether_addr(f->eth_addr) ||
 		     is_zero_ether_addr(f->eth_addr))) {
-			int rc = vxlan_fdb_append(f, ip, port, vni, ifindex,
-						  &rd);
+			rc = vxlan_fdb_append(f, ip, port, vni, ifindex, &rd);
 
 			if (rc < 0)
 				return rc;
@@ -673,7 +673,11 @@ static int vxlan_fdb_create(struct vxlan_dev *vxlan,
 		INIT_LIST_HEAD(&f->remotes);
 		memcpy(f->eth_addr, mac, ETH_ALEN);
 
-		vxlan_fdb_append(f, ip, port, vni, ifindex, &rd);
+		rc = vxlan_fdb_append(f, ip, port, vni, ifindex, &rd);
+		if (rc < 0) {
+			kfree(f);
+			return rc;
+		}
 
 		++vxlan->addrcnt;
 		hlist_add_head_rcu(&f->hlist,