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Subject[PATCH 3.2 59/61] net: cdc_ether: fix divide by 0 on bad descriptors
3.2.96-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Bjørn Mork <bjorn@mork.no>

commit 2cb80187ba065d7decad7c6614e35e07aec8a974 upstream.

Setting dev->hard_mtu to 0 will cause a divide error in
usbnet_probe. Protect against devices with bogus CDC Ethernet
functional descriptors by ignoring a zero wMaxSegmentSize.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: parsing code is organised differently]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -234,8 +234,9 @@ int usbnet_generic_cdc_bind(struct usbne
info->ether->bLength);
goto bad_desc;
}
- dev->hard_mtu = le16_to_cpu(
- info->ether->wMaxSegmentSize);
+ if (info->ether->wMaxSegmentSize)
+ dev->hard_mtu = le16_to_cpu(
+ info->ether->wMaxSegmentSize);
/* because of Zaurus, we may be ignoring the host
* side link address we were given.
*/
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