linux-kernel - Re: [PATCH] bitmap: bitmap_parse takes a kernel buffer instead of a user buffer

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Date:	Tue, 3 Oct 2006 16:39:36 -0700
From:	Andrew Morton <akpm@...l.org>
To:	Reinette Chatre <reinette.chatre@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org,
	Inaky Perez-Gonzalez <inaky@...ux.intel.com>,
	Paul Jackson <pj@....com>
Subject: Re: [PATCH] bitmap: bitmap_parse takes a kernel buffer instead of a
 user buffer

On Tue, 3 Oct 2006 08:16:27 -0700
Reinette Chatre <reinette.chatre@...ux.intel.com> wrote:

> lib/bitmap.c:bitmap_parse() is a library function that received as input a  user buffer. This seemed to have originated from the way the write_proc function of the /proc filesystem operates.
> 
> This function will be useful for other uses as well; for example, taking input  for /sysfs instead of /proc, so it was changed to accept kernel buffers. We have this use for the Linux UWB project, as part as the upcoming bandwidth allocator code.
> 
> Only a few routines used this function and they were changed too.

Fair enough.  But this:

>  
> -	err = cpumask_parse(buffer, count, new_value);
> +	kbuf = kmalloc(count, GFP_KERNEL);
> +	if (kbuf == NULL)
> +		return -ENOMEM;
> +	ret = copy_from_user(kbuf, buffer, count);
> +	if (ret != 0) {
> +		kfree(kbuf);
> +		return -EFAULT;
> +	}
> +	err = cpumask_parse(kbuf, count, new_value);
> +	kfree(kbuf);
>  	if (err)
>  		return err;
>
> ...
>
> -	err = cpumask_parse(buffer, count, new_value);
> +	kbuf = kmalloc(count, GFP_KERNEL);
> +	if (kbuf == NULL)
> +		return -ENOMEM;
> +	ret = copy_from_user(kbuf, buffer, count);
> +	if (ret != 0) {
> +		kfree(kbuf);
> +		return -EFAULT;
> +	}
> +	err = cpumask_parse(kbuf, count, new_value);
> +	kfree(kbuf);
>  	if (err)
>  		return err;
>  

is sending us a message ;)

How about adding a new bitmap_parse_user() (and cpumask_parse_user()) which
does the above?
-
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