net: calxedaxgmac: throw away overrun frames

From: Rob Herring <[email protected]>

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.

---
 drivers/net/ethernet/calxeda/xgmac.c |    4 ++++
 1 file changed, 4 insertions(+)

index b407043..f7f0290 100644
@@ -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))

1.7.10.4

From: Rob Herring <[email protected]>
Date: Wed, 16 Jan 2013 17:36:37 -0600

Applied.