[PATCH] usbnet: sanity check for maxpacket

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

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+76bb1d34ffa0adc03baa@syzkaller.appspotmail.com
---
 drivers/net/usb/usbnet.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 840c1c2ab16a..396f5e677bf0 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c

@@ -1788,6 +1788,9 @@ 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))

-- 
2.26.2

On Wed, Oct 20, 2021 at 11:17:33AM +0200, Oliver Neukum wrote:

maxpacket of 0 makes no sense and oopdses as we need to divide

typo: oopses

I'd prefer brackets here since it's a multi-line block. Or just drop the
comment.

 
 	/* let userspace know we have a random address */
 	if (ether_addr_equal(net->dev_addr, node_id))

Other than that, looks good:

Reviewed-by: Johan Hovold <johan@kernel.org>

Johan