Patch "packet: only allow extra vlan len on ethernet devices" has been added to the 4.2-stable tree

@@ -1622,6 +1622,20 @@ static void fanout_release(struct sock *
 		kfree_rcu(po->rollover, rcu);
 }
 
+static bool packet_extra_vlan_len_allowed(const struct net_device *dev,
+					  struct sk_buff *skb)
+{
+	/* Earlier code assumed this would be a VLAN pkt, double-check
+	 * this now that we have the actual packet in hand. We can only
+	 * do this check on Ethernet devices.
+	 */
+	if (unlikely(dev->type != ARPHRD_ETHER))
+		return false;
+
+	skb_reset_mac_header(skb);
+	return likely(eth_hdr(skb)->h_proto == htons(ETH_P_8021Q));
+}
+
 static const struct proto_ops packet_ops;
 
 static const struct proto_ops packet_ops_spkt;

@@ -1783,18 +1797,10 @@ retry:
 		goto retry;
 	}
 
-	if (len > (dev->mtu + dev->hard_header_len + extra_len)) {
-		/* Earlier code assumed this would be a VLAN pkt,
-		 * double-check this now that we have the actual
-		 * packet in hand.
-		 */
-		struct ethhdr *ehdr;
-		skb_reset_mac_header(skb);
-		ehdr = eth_hdr(skb);
-		if (ehdr->h_proto != htons(ETH_P_8021Q)) {
-			err = -EMSGSIZE;
-			goto out_unlock;
-		}
+	if (len > (dev->mtu + dev->hard_header_len + extra_len) &&
+	    !packet_extra_vlan_len_allowed(dev, skb)) {
+		err = -EMSGSIZE;
+		goto out_unlock;
 	}
 
 	skb->protocol = proto;

@@ -2406,18 +2412,10 @@ static int tpacket_snd(struct packet_soc
 		tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto,
 					  addr, hlen);
 		if (likely(tp_len >= 0) &&
-		    tp_len > dev->mtu + dev->hard_header_len) {
-			struct ethhdr *ehdr;
-			/* Earlier code assumed this would be a VLAN pkt,
-			 * double-check this now that we have the actual
-			 * packet in hand.
-			 */
+		    tp_len > dev->mtu + dev->hard_header_len &&
+		    !packet_extra_vlan_len_allowed(dev, skb))
+			tp_len = -EMSGSIZE;
 
-			skb_reset_mac_header(skb);
-			ehdr = eth_hdr(skb);
-			if (ehdr->h_proto != htons(ETH_P_8021Q))
-				tp_len = -EMSGSIZE;
-		}
 		if (unlikely(tp_len < 0)) {
 			if (po->tp_loss) {
 				__packet_set_status(po, ph,

@@ -2638,18 +2636,10 @@ static int packet_snd(struct socket *soc
 
 	sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
 
-	if (!gso_type && (len > dev->mtu + reserve + extra_len)) {
-		/* Earlier code assumed this would be a VLAN pkt,
-		 * double-check this now that we have the actual
-		 * packet in hand.
-		 */
-		struct ethhdr *ehdr;
-		skb_reset_mac_header(skb);
-		ehdr = eth_hdr(skb);
-		if (ehdr->h_proto != htons(ETH_P_8021Q)) {
-			err = -EMSGSIZE;
-			goto out_free;
-		}
+	if (!gso_type && (len > dev->mtu + reserve + extra_len) &&
+	    !packet_extra_vlan_len_allowed(dev, skb)) {
+		err = -EMSGSIZE;
+		goto out_free;
 	}
 
 	skb->protocol = proto;