[PATCH] usbnet.c, buf.overrun crash-bugfix, Kernel 2.6.12-rc1

[Jakemuksen spammiosote <jhroska@byterapers.com>]

Atleast versions 2.6.5 - 2.6.12-rc1 crash if an USB device using usbnet 
sends oversized packet. Such packets occur most likely with broken
device. Here's a patch that throws away such packet, to keep the machine
from crashing. Hopefully this doesn't leave memory unreleased. If it does, 
it's still better than crashing as such oversized packets are really rare.

Signed-off-by: Jarkko Hakala <jhroska@byterapers.com>

diff -Nur linux-2.6.12-rc1-orig/drivers/usb/net/usbnet.c 
linux-2.6.12-rc1/drivers/usb/net/usbnet.c
--- linux-2.6.12-rc1-orig/drivers/usb/net/usbnet.c      2005-03-18 
03:34:13.000000000 +0200
+++ linux-2.6.12-rc1/drivers/usb/net/usbnet.c   2005-03-24 
16:46:08.000000000 +0200
@@ -2795,9 +2795,20 @@
         struct usbnet           *dev = entry->dev;
         int                     urb_status = urb->status;

-       skb_put (skb, urb->actual_length);
-       entry->state = rx_done;
-       entry->urb = NULL;
+       if (unlikely((skb->tail + urb->actual_length) > skb->end)) {
+               entry->state = rx_cleanup;
+               dev->stats.rx_errors++;
+               dev->stats.rx_length_errors++;
+               entry->urb = NULL;
+               printk(KERN_ERR
+                      "USB RX packet too long, discarded. "
+                      "Your slave device most likely is broken\n");
+               /* lets hope upper level protocols will recover */
+       } else {
+               skb_put(skb, urb->actual_length);
+               entry->state = rx_done;
+               entry->urb = NULL;
+       }

         switch (urb_status) {
             // success