linux-kernel - Re: [PATCH] firewire: cdev: fix information leak

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Date:	Wed, 07 Apr 2010 08:30:50 +0200
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	linux1394-devel@...ts.sourceforge.net
CC:	Clemens Ladisch <clemens@...isch.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firewire: cdev: fix information leak

Stefan Richter wrote:
> --- a/drivers/firewire/core-cdev.c
> +++ b/drivers/firewire/core-cdev.c
> @@ -1346,41 +1346,43 @@ static int (* const ioctl_handlers[])(st
>  static int dispatch_ioctl(struct client *client,
>  			  unsigned int cmd, void __user *arg)
>  {
>  	union ioctl_arg buffer;
>  	int ret;
>  
>  	if (fw_device_is_shutdown(client->device))
>  		return -ENODEV;
>  
>  	if (_IOC_TYPE(cmd) != '#' ||
>  	    _IOC_NR(cmd) >= ARRAY_SIZE(ioctl_handlers))
>  		return -EINVAL;
>  
> -	if (_IOC_DIR(cmd) & _IOC_WRITE) {
> -		if (_IOC_SIZE(cmd) > sizeof(buffer) ||
> -		    copy_from_user(&buffer, arg, _IOC_SIZE(cmd)))
> +	if (_IOC_SIZE(cmd) > sizeof(buffer))
> +		return -EFAULT;

I'll combine this into the preceding -EINVAL return.  Cf. man ioctl.

> +
> +	if (_IOC_DIR(cmd) == _IOC_READ)
> +		memset(&buffer, 0, _IOC_SIZE(cmd));
> +
> +	if (_IOC_DIR(cmd) & _IOC_WRITE)
> +		if (copy_from_user(&buffer, arg, _IOC_SIZE(cmd)))
>  			return -EFAULT;
> -	}
>  
>  	ret = ioctl_handlers[_IOC_NR(cmd)](client, &buffer);
>  	if (ret < 0)
>  		return ret;
>  
> -	if (_IOC_DIR(cmd) & _IOC_READ) {
> -		if (_IOC_SIZE(cmd) > sizeof(buffer) ||
> -		    copy_to_user(arg, &buffer, _IOC_SIZE(cmd)))
> +	if (_IOC_DIR(cmd) & _IOC_READ)
> +		if (copy_to_user(arg, &buffer, _IOC_SIZE(cmd)))
>  			return -EFAULT;
> -	}
>  
>  	return ret;
>  }

-- 
Stefan Richter
-=====-==-=- -=-- --===
http://arcgraph.de/sr/
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