Re: [PATCH 02/10] USB: cdc-acm: more sanity checking

[Lu Baolu <baolu.lu@linux.intel.com>]

I am sorry. This email was sent out due to an incorrect operation.
Please ignore it. I am sorry for disturbing you.

Best regards,
Baolu

On 03/25/2016 10:58 AM, Lu Baolu wrote:
> From: Oliver Neukum <oneukum@suse.com>
>
> An attack has become available which pretends to be a quirky
> device circumventing normal sanity checks and crashes the kernel
> by an insufficient number of interfaces. This patch adds a check
> to the code path for quirky devices.
>
> Signed-off-by: Oliver Neukum <ONeukum@suse.com>
> CC: stable@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/usb/class/cdc-acm.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
> index 1d2c99a..83fd30b 100644
> --- a/drivers/usb/class/cdc-acm.c
> +++ b/drivers/usb/class/cdc-acm.c
> @@ -1179,6 +1179,9 @@ static int acm_probe(struct usb_interface *intf,
>  	if (quirks == NO_UNION_NORMAL) {
>  		data_interface = usb_ifnum_to_if(usb_dev, 1);
>  		control_interface = usb_ifnum_to_if(usb_dev, 0);
> +		/* we would crash */
> +		if (!data_interface || !control_interface)
> +			return -ENODEV;
>  		goto skip_normal_probe;
>  	}
>