netdev - [PATCH] usbnet: sanity check for maxpacket

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Date:   Wed, 20 Oct 2021 11:17:33 +0200
From:   Oliver Neukum <oneukum@...e.com>
To:     syzkaller-bugs@...glegroups.com, netdev@...r.kernel.org,
        linux-usb@...r.kernel.org, davem@...emloft.net, kuba@...nel.org
Cc:     Oliver Neukum <oneukum@...e.com>,
        syzbot+76bb1d34ffa0adc03baa@...kaller.appspotmail.com
Subject: [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@...e.com>
Reported-by: syzbot+76bb1d34ffa0adc03baa@...kaller.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