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Date:   Tue, 26 Oct 2021 14:33:57 +0200
From:   Johan Hovold <johan@kernel.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Oliver Neukum <oneukum@suse.com>,
        syzbot+76bb1d34ffa0adc03baa@syzkaller.appspotmail.com,
        Jakub Kicinski <kuba@kernel.org>
Subject: Re: [PATCH 5.14 165/169] usbnet: sanity check for maxpacket
Message-ID: <YXf1tdKi0b0M4XCx@hovoldconsulting.com>
References: <20211025191017.756020307@linuxfoundation.org>
 <20211025191038.360463849@linuxfoundation.org>
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On Mon, Oct 25, 2021 at 09:15:46PM +0200, Greg Kroah-Hartman wrote:
> 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>

Please drop this one from all stable queues until

	https://lore.kernel.org/r/20211026124015.3025136-1-wanghai38@huawei.com

has landed.

> ---
>  drivers/net/usb/usbnet.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> --- a/drivers/net/usb/usbnet.c
> +++ b/drivers/net/usb/usbnet.c
> @@ -1788,6 +1788,10 @@ 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))

Johan