net: cdc_ether: fix divide by 0 on bad descriptors

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>
This commit is contained in:
Bjørn Mork 2017-11-06 15:37:22 +01:00 committed by David S. Miller
parent b5f862180d
commit 2cb80187ba

View File

@ -230,7 +230,7 @@ skip:
goto bad_desc;
}
if (header.usb_cdc_ether_desc) {
if (header.usb_cdc_ether_desc && 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.