sky2: check drop truncated packets

Backport of commit 71749531

If packet larger than MTU is received, the driver uses hardware to
truncate the packet. Use the status registers to catch/drop them.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/net/sky2.c

@@ -2065,6 +2065,9 @@ static struct sk_buff *sky2_receive(struct net_device *dev,
 	if (!(status & GMR_FS_RX_OK))
 		goto resubmit;
 
+	if (status >> 16 != length)
+		goto len_mismatch;
+
 	if (length < copybreak)
 		skb = receive_copy(sky2, re, length);
 	else
@@ -2074,6 +2077,11 @@ static struct sk_buff *sky2_receive(struct net_device *dev,
 
 	return skb;
 
+len_mismatch:
+	/* Truncation of overlength packets
+	   causes PHY length to not match MAC length */
+	++sky2->net_stats.rx_length_errors;
+
 error:
 	++sky2->net_stats.rx_errors;
 	if (status & GMR_FS_RX_FF_OV) {