mlx4_en: Fix read buffer overflow in mlx4_en_complete_rx_desc()

If the length is less or equal to frag_prefix_size in the first iteration
we write skb_frags_rx[-1] and read from priv->frag_info[-1]

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/mlx4/en_rx.c b/drivers/net/mlx4/en_rx.c
index 91bdfdf..3ac0404 100644 (file)
--- a/drivers/net/mlx4/en_rx.c
+++ b/drivers/net/mlx4/en_rx.c
@@ -506,8 +506,9 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv,
                                 PCI_DMA_FROMDEVICE);
        }
        /* Adjust size of last fragment to match actual length */
-       skb_frags_rx[nr - 1].size = length -
-               priv->frag_info[nr - 1].frag_prefix_size;
+       if (nr > 0)
+               skb_frags_rx[nr - 1].size = length -
+                       priv->frag_info[nr - 1].frag_prefix_size;
        return nr;
 
 fail: