ACK/cmnt: [PATCH] usbip: fix stub_rx: get_pipe() to validate endpoint number

[Juerg Haefliger]

On 07/19/2018 07:17 PM, Colin King wrote:
> From: Shuah Khan <shuahkh at osg.samsung.com>
> 
> CVE-2017-16912
> 
> get_pipe() routine doesn't validate the input endpoint number
> and uses to reference ep_in and ep_out arrays. Invalid endpoint
> number can trigger BUG(). Range check the epnum and returning
> error instead of calling BUG().
> 
> Change caller stub_recv_cmd_submit() to handle the get_pipe()
> error return.
> 
> Reported-by: Secunia Research <vuln at secunia.com>
> Cc: stable <stable at vger.kernel.org>
> Signed-off-by: Shuah Khan <shuahkh at osg.samsung.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> (backported from upstream commit 635f545a7e8be7596b9b2b6a43cab6bbd5a88e43)

(backported from commit 635f545a7e8be7596b9b2b6a43cab6bbd5a88e43)
[cking: Accounted for file rename drivers/usb/usbip/stub_rx.c ->
 drivers/staging/usbip/stub_rx.c.]


> Signed-off-by: Colin Ian King <colin.king at canonical.com>

Acked-by: Juerg Haefliger <juergh at canonical.com>

...Juerg


> ---
>  drivers/staging/usbip/stub_rx.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/staging/usbip/stub_rx.c b/drivers/staging/usbip/stub_rx.c
> index db48a78..f071048 100644
> --- a/drivers/staging/usbip/stub_rx.c
> +++ b/drivers/staging/usbip/stub_rx.c
> @@ -355,16 +355,15 @@ static int get_pipe(struct stub_device *sdev, int epnum, int dir)
>  	struct usb_host_endpoint *ep;
>  	struct usb_endpoint_descriptor *epd = NULL;
>  
> +	if (epnum < 0 || epnum > 15)
> +		goto err_ret;
> +
>  	if (dir == USBIP_DIR_IN)
>  		ep = udev->ep_in[epnum & 0x7f];
>  	else
>  		ep = udev->ep_out[epnum & 0x7f];
> -	if (!ep) {
> -		dev_err(&sdev->interface->dev, "no such endpoint?, %d\n",
> -			epnum);
> -		BUG();
> -	}
> -
> +	if (!ep)
> +		goto err_ret;
>  	epd = &ep->desc;
>  	if (usb_endpoint_xfer_control(epd)) {
>  		if (dir == USBIP_DIR_OUT)
> @@ -394,8 +393,9 @@ static int get_pipe(struct stub_device *sdev, int epnum, int dir)
>  			return usb_rcvisocpipe(udev, epnum);
>  	}
>  
> +err_ret:
>  	/* NOT REACHED */
> -	dev_err(&sdev->interface->dev, "get pipe, epnum %d\n", epnum);
> +	dev_err(&sdev->udev->dev, "get pipe() invalid epnum %d\n", epnum);
>  	return 0;
>  }
>  
> @@ -462,6 +462,9 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
>  	struct usb_device *udev = sdev->udev;
>  	int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);
>  
> +	if (pipe == -1)
> +		return;
> +
>  	priv = stub_priv_alloc(sdev, pdu);
>  	if (!priv)
>  		return;
> 


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