Re: [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On 03/13/2017 05:49 AM, Johan Hovold wrote:
> Make sure to check the number of endpoints to avoid dereferencing a
> NULL-pointer should a malicious device lack endpoints.

Is this theory or was it actually observed ?

Thanks,
Guenter

> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
> ---
>  drivers/watchdog/pcwd_usb.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/watchdog/pcwd_usb.c b/drivers/watchdog/pcwd_usb.c
> index 99ebf6ea3de6..5615f4013924 100644
> --- a/drivers/watchdog/pcwd_usb.c
> +++ b/drivers/watchdog/pcwd_usb.c
> @@ -630,6 +630,9 @@ static int usb_pcwd_probe(struct usb_interface *interface,
>  		return -ENODEV;
>  	}
>
> +	if (iface_desc->desc.bNumEndpoints < 1)
> +		return -ENODEV;
> +
>  	/* check out the endpoint: it has to be Interrupt & IN */
>  	endpoint = &iface_desc->endpoint[0].desc;