Date: Mon, 23 Oct 2006 22:02:03 +0200
To: "Greg KH" <gregkh@suse.de>
Subject: Re: [PATCH] 2.6.19-rc2-mm2 sysfs: sysfs_write_file() writes zero terminated data
Reply-To: balagi@justmail.de
From: "Thomas Maier" <balagi@justmail.de>
Cc: linux-kernel@vger.kernel.org
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Hello,

Sorry, maybe i missed something, but according to the
code in fs/sysfs/file.c the "write" sequence is:

- call to sysfs_write_file(ubuf, count)
- if (!sysfsbuf->page)  alloc zeroed page
- copy count bytes from ubuf to sysfsbuf->page
- call store(sysfsbuf->page, count)

When you write again to the file before closing it
(possible?!), and count is less the the previous count
you may not pass a zero terminated string/data to store().

-Thomas


Am 22.10.2006, 20:39 Uhr, schrieb Greg KH <gregkh@suse.de>:

> On Sun, Oct 22, 2006 at 07:17:47PM +0200, Thomas Maier wrote:
>> Hello,
>>
>> since most of the files in sysfs are text files,
>> it would be nice, if the "store" function called
>> during sysfs_write_file() gets a zero terminated
>> string / data.
>> The current implementation seems not to ensure this.
>> (But only if it is the first time the zeroed buffer
>> page is allocated.)
>
> Have you seen sysfs buffers being passed to the store() function in a
> non-null terminated manner?  How?
>
> Are you seeking backward and then writing again to the file somehow?
>
> thanks,
>
> greg k-h
>
>


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