usbnet: sanity check for maxpacket

maxpacket of 0 makes no sense and oopses as we need to divide
by it. Give up.

V2: fixed typo in log and stylistic issues

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+76bb1d34ffa0adc03baa@syzkaller.appspotmail.com
Reviewed-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20211021122944.21816-1-oneukum@suse.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 840c1c2..80432ee 100644 (file)
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1788,6 +1788,10 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
        if (!dev->rx_urb_size)
                dev->rx_urb_size = dev->hard_mtu;
        dev->maxpacket = usb_maxpacket (dev->udev, dev->out, 1);
+       if (dev->maxpacket == 0) {
+               /* that is a broken device */
+               goto out4;
+       }
 
        /* let userspace know we have a random address */
        if (ether_addr_equal(net->dev_addr, node_id))