pasemi_mac: Fix reuse of free'd skb

Turns out we're freeing the skb when we detect CRC error, but we're
not clearing out info->skb. We could either clear it and have the stack
reallocate it, or just leave it and the rx ring refill code will reuse
the one that was allocated.

Reusing a freed skb obviously caused some nasty crashes of various kind,
as reported by Brent Baude and David Woodhouse.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/pasemi_mac.c

@@ -586,7 +586,7 @@ static int pasemi_mac_clean_rx(struct pasemi_mac *mac, int limit)
 			/* CRC error flagged */
 			mac->netdev->stats.rx_errors++;
 			mac->netdev->stats.rx_crc_errors++;
-			dev_kfree_skb_irq(skb);
+			/* No need to free skb, it'll be reused */
 			goto next;
 		}