linux-kernel - Re: [PATCH] Use kzfree in tty buffer management to enforce data sanitization

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Message-ID: <84144f020905302327t36966003ufce87cf646d649a6@mail.gmail.com>
Date:	Sun, 31 May 2009 09:27:09 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	"Larry H." <research@...reption.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Rik van Riel <riel@...hat.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] Use kzfree in tty buffer management to enforce data 
	sanitization

Hi Larry,

On Sat, 30 May 2009, Larry H. wrote:
>>> This patch doesn't affect fastpaths.

On 19:04 Sat 30 May, Linus Torvalds wrote:
>> This patch is ugly as hell.
>>
>> You already know the size of the data to clear.
>>
>> If we actually wanted this (and I am in _no_way_ saying we do), the only
>> sane thing to do is to just do
>>
>>       memset(buf->data, 0, N_TTY_BUF_SIZE);
>>       if (PAGE_SIZE != N_TTY_BUF_SIZE)
>>               kfree(...)
>>       else
>>               free_page(...)
>>

On Sun, May 31, 2009 at 5:35 AM, Larry H. <research@...reption.com> wrote:
> It wasn't me who proposed using kzfree in these places. Ask Ingo and
> Peter or refer to the entire thread about my previous patches.

Nobody suggested using kzfree() in this _specific_place_. It's obvious
that memset() is a better solution here given the current constraints
of the code as demonstrated by Linus' patch.

                                       Pekka
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