af_packet: Check return of dev_set_promiscuity/allmulti

dev_set_promiscuity/allmulti might overflow.  Commit: "netdevice: Fix
promiscuity and allmulti overflow" in net-next makes
dev_set_promiscuity/allmulti return error number if overflow happened.

In af_packet, we check all positive increment for promiscuity and
allmulti to get error return.

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Acked-by: Patrick McHardy <kaber@trash.net> 
Signed-off-by: David S. Miller <davem@davemloft.net>

net/packet/af_packet.c

@@ -1173,7 +1173,8 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
 	return 0;
 }
 
-static void packet_dev_mc(struct net_device *dev, struct packet_mclist *i, int what)
+static int packet_dev_mc(struct net_device *dev, struct packet_mclist *i,
+			 int what)
 {
 	switch (i->type) {
 	case PACKET_MR_MULTICAST:
@@ -1183,13 +1184,14 @@ static void packet_dev_mc(struct net_device *dev, struct packet_mclist *i, int w
 			dev_mc_delete(dev, i->addr, i->alen, 0);
 		break;
 	case PACKET_MR_PROMISC:
-		dev_set_promiscuity(dev, what);
+		return dev_set_promiscuity(dev, what);
 		break;
 	case PACKET_MR_ALLMULTI:
-		dev_set_allmulti(dev, what);
+		return dev_set_allmulti(dev, what);
 		break;
 	default:;
 	}
+	return 0;
 }
 
 static void packet_dev_mclist(struct net_device *dev, struct packet_mclist *i, int what)
@@ -1243,7 +1245,11 @@ static int packet_mc_add(struct sock *sk, struct packet_mreq_max *mreq)
 	i->count = 1;
 	i->next = po->mclist;
 	po->mclist = i;
-	packet_dev_mc(dev, i, +1);
+	err = packet_dev_mc(dev, i, 1);
+	if (err) {
+		po->mclist = i->next;
+		kfree(i);
+	}
 
 done:
 	rtnl_unlock();