[16/20] asix: fix infinite loop in rx_fixup()

[Greg KH <gregkh@suse.de>]

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Aurelien Jacobs <aurel@gnuage.org>

commit 6c15d74defd38e7e7f8805392578b7a1d508097e upstream.

At this point if skb->len happens to be 2, the subsequant skb_pull(skb, 4)
call won't work and the skb->len won't be decreased and won't ever reach 0,
resulting in an infinite loop.

With an ASIX 88772 under heavy load, without this patch, rx_fixup() reaches
an infinite loop in less than a minute. With this patch applied,
no infinite loop even after hours of heavy load.

Signed-off-by: Aurelien Jacobs <aurel@gnuage.org>
Cc: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

---
 drivers/net/usb/asix.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/usb/asix.c
+++ b/drivers/net/usb/asix.c
@@ -339,7 +339,7 @@ static int asix_rx_fixup(struct usbnet *
 
 		skb_pull(skb, (size + 1) & 0xfffe);
 
-		if (skb->len == 0)
+		if (skb->len < sizeof(header))
 			break;
 
 		head = (u8 *) skb->data;