linux-kernel - RE: [PATCH] phy: fix compiler array bounds warning on settings[]

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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D0F6D1D1E@AcuExch.aculab.com>
Date:	Wed, 5 Mar 2014 15:10:34 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Bjorn Helgaas' <bhelgaas@...gle.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] phy: fix compiler array bounds warning on settings[]

From: Bjorn Helgaas
> On Wed, Mar 5, 2014 at 2:10 AM, David Laight <David.Laight@...lab.com> wrote:
> > From: Bjorn Helgaas
> >> With -Werror=array-bounds, gcc v4.7.x warns that in phy_find_valid(), the
> >> settings[] "array subscript is above array bounds", I think because idx is
> >> a signed integer and if the caller supplied idx < 0, we pass the guard but
> >> still reference out of bounds.
> >
> > Not rejecting the patch but...
> >
> > Just indexing an array with 'int' shouldn't cause this warning,
> > so somewhere a caller must actually be passing an idx < 0.
> >
> > While changing the type to unsigned will make the comparison
> > against the array bound reject the -1, I suspect that the
> > specific call path didn't really intend passing a hard-coded -1.
> >
> > It might be worth trying to locate the call site that passes -1.
> 
> I agree 100%.  If that's the case, we definitely should find that
> caller rather than apply this patch.  I'll look more today.

You might want to apply the patch as well :-)

	David