linux-kernel - Re: [PATCH v2] lib: gcd: prevent possible div by 0

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Date:	Wed, 12 Sep 2012 21:20:30 +0200
From:	Davidlohr Bueso <dave@....org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	lkml <linux-kernel@...r.kernel.org>, stable@...r.kernel.org
Subject: Re: [PATCH v2] lib: gcd: prevent possible div by 0

On Wed, 2012-09-12 at 12:10 -0700, Andrew Morton wrote:
> On Mon, 10 Sep 2012 16:35:19 +0200
> Davidlohr Bueso <dave@....org> wrote:
> 
> > Account for all properties when a and/or b are 0:
> > gcd(0, 0) = 0
> > gcd(a, 0) = a
> > gcd(0, b) = b
> > 
> > Cc: stable@...r.kernel.org
> 
> Why cc:stable?  If this patch fixes some known problem in the current
> kernel then that really really should have been described in the
> changelog.  Always.  Please.

Ok, I will keep it in mind next time. No known problem (at least that I
know of), but due to the nature of the potential bug, I thought that it
was worth adding it to stable.

Thanks.

> 
> > ...
> > --- a/lib/gcd.c
> > +++ b/lib/gcd.c
> > @@ -9,6 +9,9 @@ unsigned long gcd(unsigned long a, unsigned long b)
> >  
> >  	if (a < b)
> >  		swap(a, b);
> > +
> > +	if (!b)
> > +		return a;
> >  	while ((r = a % b) != 0) {
> >  		a = b;
> >  		b = r;
> > -- 
> > 1.7.9.5
> > 
> > 
> 


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