[PATCH 5.4 54/58] usbnet: sanity check for maxpacket

Greg Kroah-Hartman
2021-10-25T19:36:35Z

From: Oliver Neukum <oneukum@suse.com>

commit 397430b50a363d8b7bdda00522123f82df6adc5e upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/usb/usbnet.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1773,6 +1773,10 @@ usbnet_probe (struct usb_interface *udev
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))