linux-kernel - Re: [PATCH] Input: xpad - validate USB endpoint type during probe

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Message-ID: <20170912182844.GA6654@dtor-ws>
Date:   Tue, 12 Sep 2017 11:28:44 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Cameron Gutman <aicommander@...il.com>
Cc:     rojtberg@...il.com, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, andreyknvl@...gle.com
Subject: Re: [PATCH] Input: xpad - validate USB endpoint type during probe

On Tue, Sep 12, 2017 at 11:12:12AM -0700, Cameron Gutman wrote:
> We should only see devices with interrupt endpoints. Ignore any other
> endpoints that we find, so we don't send try to send them interrupt URBs
> and trigger a WARN down in the USB stack.
> 
> Reported-by: Andrey Konovalov <andreyknvl@...gle.com>
> Tested-by: Andrey Konovalov <andreyknvl@...gle.com>
> Cc: <stable@...r.kernel.org> # c01b5e7464f0 Input: xpad - don't depend on endpoint order
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Cameron Gutman <aicommander@...il.com>

Applied, thank you.

> ---
> To be able to hit any of the LTS kernels, we'll need to also cherry pick
> c01b5e7464f0 ("Input: xpad - don't depend on endpoint order"). In hindsight,
> this commit also addresses a malicious USB device case, since a device could
> purposefully trick us into sending URBs to an endpoint in the wrong direction.
> ---
>  drivers/input/joystick/xpad.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c
> index f8e34ef643c7..d86e59515b9c 100644
> --- a/drivers/input/joystick/xpad.c
> +++ b/drivers/input/joystick/xpad.c
> @@ -1764,10 +1764,12 @@ static int xpad_probe(struct usb_interface *intf, const struct usb_device_id *id
>  		struct usb_endpoint_descriptor *ep =
>  				&intf->cur_altsetting->endpoint[i].desc;
>  
> -		if (usb_endpoint_dir_in(ep))
> -			ep_irq_in = ep;
> -		else
> -			ep_irq_out = ep;
> +		if (usb_endpoint_xfer_int(ep)) {
> +			if (usb_endpoint_dir_in(ep))
> +				ep_irq_in = ep;
> +			else
> +				ep_irq_out = ep;
> +		}
>  	}
>  
>  	if (!ep_irq_in || !ep_irq_out) {
> -- 
> 2.14.1

-- 
Dmitry