linux-kernel - Re: [PATCH] crypto: blkcipher_get_spot() handling of buffer at end of page

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Message-Id: <200709102146.47655.ioe-lkml@rameria.de>
Date:	Mon, 10 Sep 2007 21:46:46 +0200
From:	Ingo Oeser <ioe-lkml@...eria.de>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Bob Gilligan <gilligan@...tta.com>, linux-kernel@...r.kernel.org,
	Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH] crypto: blkcipher_get_spot() handling of buffer at end of page

Hi Herbert,

On Monday 10 September 2007, Herbert Xu wrote:
> On Sat, Sep 08, 2007 at 12:14:23PM +0800, Herbert Xu wrote:
> > 
> > [CRYPTO] blkcipher: Fix handling of kmalloc page straddling
> 
> As Bob correctly noted, I had the boolean test inverted.
> Here is the correction:
> 
> [CRYPTO] blkcipher: Fix inverted test in blkcipher_get_spot
> 
> The previous patch had the conditional inverted.  This patch fixes it
> so that we return the original position if it does not straddle a page.

What about using max() for this to make your intention obvious?

static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
{
	u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK); 
	return max(start, end_page);
}


Best Regards

Ingo Oeser 
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