linux-kernel - Re: [PATCH v3] usb: misc: legousbtower: Fix buffers on stack

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Date:   Thu, 4 May 2017 15:36:23 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Maksim Salau <maksim.salau@...il.com>
Cc:     Juergen Stuber <starblue@...rs.sourceforge.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        legousb-devel@...ts.sourceforge.net, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Alfredo Rafael Vicente Boix <alviboi@...il.com>
Subject: Re: [PATCH v3] usb: misc: legousbtower: Fix buffers on stack

Hi Maksim,

Sorry for commenting this so late but..

On Tue, Apr 25, 2017 at 10:49:21PM +0300, Maksim Salau wrote:
> @@ -806,7 +814,7 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
>  	struct device *idev = &interface->dev;
>  	struct usb_device *udev = interface_to_usbdev(interface);
>  	struct lego_usb_tower *dev = NULL;
> -	struct tower_get_version_reply get_version_reply;
> +	struct tower_get_version_reply *get_version_reply = NULL;
>  	int retval = -ENOMEM;
>  	int result;
>  
> @@ -871,6 +879,13 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
>  	dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
>  	dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
>  
> +	get_version_reply = kmalloc(sizeof(*get_version_reply), GFP_KERNEL);
> +
> +	if (!get_version_reply) {
> +		retval = -ENOMEM;
> +		goto error;
> +	}
> +
>  	/* get the firmware version and log it */
>  	result = usb_control_msg (udev,
>  				  usb_rcvctrlpipe(udev, 0),
> @@ -878,18 +893,19 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
>  				  USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
>  				  0,
>  				  0,
> -				  &get_version_reply,
> -				  sizeof(get_version_reply),
> +				  get_version_reply,
> +				  sizeof(*get_version_reply),
>  				  1000);
>  	if (result < 0) {
>  		dev_err(idev, "LEGO USB Tower get version control request failed\n");
>  		retval = result;
>  		goto error;
>  	}
> -	dev_info(&interface->dev, "LEGO USB Tower firmware version is %d.%d "
> -		 "build %d\n", get_version_reply.major,
> -		 get_version_reply.minor,
> -		 le16_to_cpu(get_version_reply.build_no));
> +	dev_info(&interface->dev,
> +		 "LEGO USB Tower firmware version is %d.%d build %d\n",
> +		 get_version_reply->major,
> +		 get_version_reply->minor,
> +		 le16_to_cpu(get_version_reply->build_no));
>  
>  	/* we can register the device now, as it is ready */
>  	usb_set_intfdata (interface, dev);
> @@ -913,6 +929,7 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device

Don't you need to free get_version_reply here?

>  	return retval;
>  
>  error:
> +	kfree(get_version_reply);
>  	tower_delete(dev);
>  	return retval;
>  }


Thanks,

-- 
heikki