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

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Message-ID: <20090531112630.2c7f4f1d@lxorguk.ukuu.org.uk>
Date:	Sun, 31 May 2009 11:26:30 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Larry H." <research@...reption.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH] Use kzfree in tty buffer management to enforce data 
 sanitization

> >        memset(buf->data, 0, N_TTY_BUF_SIZE);
> >        if (PAGE_SIZE != N_TTY_BUF_SIZE)
> >                kfree(...)
> >        else
> >                free_page(...)
> >
> >
> > but quite frankly, I'm not convinced about these patches at all.
> 
> I wonder why the tty code has that N_TTY_BUF_SIZE special casing in
> the first place? I think we can probably just get rid of it and thus
> we can use kzfree() here if we want to.

Some platforms with very large page sizes override the use of page based
allocators (eg older ARM would go around allocating 32K). The normal path
is 4K or 8K page sized buffers.

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