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To: Jakub Jelinek <jakub@redhat.com>
Cc: Ulrich Drepper <drepper@redhat.com>,
	Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>,
	libc-hacker@sources.redhat.com
Subject: Re: [PATCH] xdr_array and calloc security fix
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X-Yow: Of course, you UNDERSTAND about the PLAIDS in the SPIN CYCLE --
From: Andreas Schwab <schwab@suse.de>
Date: Fri, 02 Aug 2002 04:07:00 -0000
In-Reply-To: <20020802115506.C20867@sunsite.ms.mff.cuni.cz> (Jakub Jelinek's
 message of "Fri, 2 Aug 2002 11:55:06 +0200")
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Jakub Jelinek <jakub@redhat.com> writes:

|> On Fri, Aug 02, 2002 at 02:50:40AM -0700, Ulrich Drepper wrote:
|> > Ulrich Drepper wrote:
|> > 
|> > > It should be possible to have something like
|> > > 
|> > >   ((a | b) > (a * b))
|> > > 
|> > > for unsigned values.  I'm not 100% sure, though.
|> > 
|> > I mean, this is an approximation which lets us avoid the division in 
|> > many (most?) cases.
|> 
|> Many. a=1 b=2 -> is this overflow?
|> a=0x6000000 b=64 -> this would signal no overflow, while in fact

But (a > a * b || b > a * b) should work, shouldn't it?

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
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