net/packet: fix missing net_device reference release

When using a TX ring buffer, if an error occurs processing a control
message (e.g. invalid message), the net_device reference is not
released.

Fixes c14ac94 ("sock: enable timestamping using control messages")
Signed-off-by: Douglas Caetano dos Santos <[email protected]>
Acked-by: Soheil Hassas Yeganeh <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Douglas Caetano dos Santos

net/packet/af_packet.c

@@ -2658,20 +2658,20 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
 		dev = dev_get_by_index(sock_net(&po->sk), saddr->sll_ifindex);
 	}
 
-	sockc.tsflags = po->sk.sk_tsflags;
-	if (msg->msg_controllen) {
-		err = sock_cmsg_send(&po->sk, msg, &sockc);
-		if (unlikely(err))
-			goto out;
-	}
-
 	err = -ENXIO;
 	if (unlikely(dev == NULL))
 		goto out;
 	err = -ENETDOWN;
 	if (unlikely(!(dev->flags & IFF_UP)))
 		goto out_put;
 
+	sockc.tsflags = po->sk.sk_tsflags;
+	if (msg->msg_controllen) {
+		err = sock_cmsg_send(&po->sk, msg, &sockc);
+		if (unlikely(err))
+			goto out_put;
+	}
+
 	if (po->sk.sk_socket->type == SOCK_RAW)
 		reserve = dev->hard_header_len;
 	size_max = po->tx_ring.frame_size