net: calxedaxgmac: throw away overrun frames

The xgmac driver assumes 1 frame per descriptor. If a frame larger than
the descriptor's buffer size is received, the frame will spill over into
the next descriptor. So check for received frames that span more than one
descriptor and discard them. This prevents a crash if we receive erroneous
large packets.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/net/ethernet/calxeda/xgmac.c b/drivers/net/ethernet/calxeda/xgmac.c
index b407043ce9b0..f7f02900f650 100644
--- a/drivers/net/ethernet/calxeda/xgmac.c
+++ b/drivers/net/ethernet/calxeda/xgmac.c
@@ -548,6 +548,10 @@ static int desc_get_rx_status(struct xgmac_priv *priv, struct xgmac_dma_desc *p)
                 return -1;
         }
 
+        /* All frames should fit into a single buffer */
+        if (!(status & RXDESC_FIRST_SEG) || !(status & RXDESC_LAST_SEG))
+                return -1;
+
         /* Check if packet has checksum already */
         if ((status & RXDESC_FRAME_TYPE) && (status & RXDESC_EXT_STATUS) &&
                 !(ext_status & RXDESC_IP_PAYLOAD_MASK))