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: <redacted>
---
 drivers/net/usb/usbnet.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 840c1c2ab16a..80432ee0ce69 100644
--- 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))

-- 
2.26.2

On Thu, Oct 21, 2021 at 02:29:44PM +0200, Oliver Neukum wrote:

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

Changelog goes below the ---

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: <redacted>

Again,

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

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski [off-list ref]:

On Thu, 21 Oct 2021 14:29:44 +0200 you wrote:

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: <redacted>

[...]

Here is the summary with links:
  - [PATCHv2] usbnet: sanity check for maxpacket
    https://git.kernel.org/netdev/net/c/397430b50a36

You are awesome, thank you!
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