net: cavium: liquidio: Avoid dma_unmap_single on uninitialized ndata

commit 8e6ce7eb upstream.

The label lio_xmit_failed is used 3 times through liquidio_xmit() but it
always makes a call to dma_unmap_single() using potentially
uninitialized variables from "ndata" variable. Out of the 3 gotos, 2 run
after ndata has been initialized, and had a prior dma_map_single() call.

Fix this by adding a new error label: lio_xmit_dma_failed which does
this dma_unmap_single() and then processed with the lio_xmit_failed
fallthrough.

Fixes: f21fb3ed ("Add support of Cavium Liquidio ethernet adapters")
Reported-by: coverity (CID 1309740)
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/cavium/liquidio/lio_main.c

@@ -2823,7 +2823,7 @@ static int liquidio_xmit(struct sk_buff *skb, struct net_device *netdev)
 		if (!g) {
 			netif_info(lio, tx_err, lio->netdev,
 				   "Transmit scatter gather: glist null!\n");
-			goto lio_xmit_failed;
+			goto lio_xmit_dma_failed;
 		}
 
 		cmdsetup.s.gather = 1;
@@ -2894,7 +2894,7 @@ static int liquidio_xmit(struct sk_buff *skb, struct net_device *netdev)
 	else
 		status = octnet_send_nic_data_pkt(oct, &ndata, xmit_more);
 	if (status == IQ_SEND_FAILED)
-		goto lio_xmit_failed;
+		goto lio_xmit_dma_failed;
 
 	netif_info(lio, tx_queued, lio->netdev, "Transmit queued successfully\n");
 
@@ -2908,12 +2908,13 @@ static int liquidio_xmit(struct sk_buff *skb, struct net_device *netdev)
 
 	return NETDEV_TX_OK;
 
+lio_xmit_dma_failed:
+	dma_unmap_single(&oct->pci_dev->dev, ndata.cmd.dptr,
+			 ndata.datasize, DMA_TO_DEVICE);
 lio_xmit_failed:
 	stats->tx_dropped++;
 	netif_info(lio, tx_err, lio->netdev, "IQ%d Transmit dropped:%llu\n",
 		   iq_no, stats->tx_dropped);
-	dma_unmap_single(&oct->pci_dev->dev, ndata.cmd.dptr,
-			 ndata.datasize, DMA_TO_DEVICE);
 	recv_buffer_free(skb);
 	return NETDEV_TX_OK;
 }