sh_eth: Fix padding of short frames on TX

If an skb to be transmitted is shorter than the minimum Ethernet frame
length, we currently set the DMA descriptor length to the minimum but
do not add zero-padding.  This could result in leaking sensitive
data.  We also pass different lengths to dma_map_single() and
dma_unmap_single().

Use skb_padto() to pad properly, before calling dma_map_single().

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 6576243222af74f593419e6e338cdd9387b949af..4ae22fc059181c8b001403240982aae0ec018b3c 100644 (file)
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -2117,6 +2117,9 @@ static int sh_eth_start_xmit(struct sk_buff *skb, struct net_device *ndev)
        }
        spin_unlock_irqrestore(&mdp->lock, flags);
 
+       if (skb_padto(skb, ETH_ZLEN))
+               return NETDEV_TX_OK;
+
        entry = mdp->cur_tx % mdp->num_tx_ring;
        mdp->tx_skbuff[entry] = skb;
        txdesc = &mdp->tx_ring[entry];
@@ -2126,10 +2129,7 @@ static int sh_eth_start_xmit(struct sk_buff *skb, struct net_device *ndev)
                                 skb->len + 2);
        txdesc->addr = dma_map_single(&ndev->dev, skb->data, skb->len,
                                      DMA_TO_DEVICE);
-       if (skb->len < ETH_ZLEN)
-               txdesc->buffer_length = ETH_ZLEN;
-       else
-               txdesc->buffer_length = skb->len;
+       txdesc->buffer_length = skb->len;
 
        if (entry >= mdp->num_tx_ring - 1)
                txdesc->status |= cpu_to_edmac(mdp, TD_TACT | TD_TDLE);