Date: Mon, 17 Dec 2007 19:10:17 +0100
From: Eric Dumazet <dada1@cosmosbay.com>
To: "Ray Lee" <ray-lk@madrabbit.org>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>,
       "Herbert Xu" <herbert@gondor.apana.org.au>,
       "John Reiser" <jreiser@bitwagon.com>,
       "Andrew Morton" <akpm@linux-foundation.org>, security@kernel.org,
       tytso@mit.edu,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
       mpm@selenic.com, linux-sparse@vger.kernel.org
Subject: Re: Signed divides vs shifts (Re: [Security] /dev/urandom uses
 uninit bytes, leaks user data)
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	<alpine.LFD.0.9999.0712170856050.21557@woody.linux-foundation.org>
	<20071217185557.0b501e23.dada1@cosmosbay.com>
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On Mon, 17 Dec 2007 10:05:35 -0800
"Ray Lee" <ray-lk@madrabbit.org> wrote:

> On Dec 17, 2007 9:55 AM, Eric Dumazet <dada1@cosmosbay.com> wrote:
> > -               mid = (last - first) / 2 + first;
> > +       while (low <= high) {
> > +               mid = (low + high) / 2;
> 
> I think you just introduced a bug. Think about what happens if
> low=high=MAX_LONG/2 + 1.
> 

Fortunatly this is not possible :)

Hint : sizeof(struct exception_table_entry) is >= 8

so high is garanteed to be <= MAX_LONG/8

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