linux-kernel - Re: [PATCH] DRBG: fix maximum value checks on 32 bit systems

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Message-ID: <20140826080858.GA4161@gondor.apana.org.au>
Date:	Tue, 26 Aug 2014 16:08:58 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Stephan Mueller <smueller@...onox.de>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] DRBG: fix maximum value checks on 32 bit systems

On Tue, Aug 26, 2014 at 10:06:52AM +0200, Stephan Mueller wrote:
> The maximum values for additional input string or generated blocks is
> larger than 1<<32. To ensure a sensible value on 32 bit systems, return
> SIZE_MAX on 32 bit systems. This value is lower than the maximum allowed
> values defined in SP800-90A. The standard allow lower maximum values,
> but not larger values.
> 
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Reported-by: kbuild test robot <fengguang.wu@...el.com>
> Signed-off-by: Stephan Mueller <smueller@...onox.de>

Unfortunately there's a place in drbg where you add one to
drbg_max_addtl which will cause it to overflow back to zero.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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