netdev - Re: [PATCHv2] usbnet: sanity check for maxpacket

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Message-ID: <YXFfMCZA3XHzHfgQ@hovoldconsulting.com>
Date:   Thu, 21 Oct 2021 14:38:08 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Oliver Neukum <oneukum@...e.com>
Cc:     syzkaller-bugs@...glegroups.com, netdev@...r.kernel.org,
        linux-usb@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        syzbot+76bb1d34ffa0adc03baa@...kaller.appspotmail.com
Subject: Re: [PATCHv2] usbnet: sanity check for maxpacket

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@...e.com>
> Reported-by: syzbot+76bb1d34ffa0adc03baa@...kaller.appspotmail.com

Again,

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

> ---
>  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))