linux-kernel - Re: [PATCH 08/11] x86: make TASK_SIZE

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Message-ID: <202008181258.CEC4B8B3@keescook>
Date:   Tue, 18 Aug 2020 12:59:05 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Michael Ellerman <mpe@...erman.id.au>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 08/11] x86: make TASK_SIZE_MAX usable from assembly code

On Tue, Aug 18, 2020 at 09:55:39PM +0200, Christoph Hellwig wrote:
> On Tue, Aug 18, 2020 at 12:44:49PM -0700, Kees Cook wrote:
> > On Mon, Aug 17, 2020 at 09:32:09AM +0200, Christoph Hellwig wrote:
> > > For 64-bit the only hing missing was a strategic _AC, and for 32-bit we
> > 
> > typo: thing
> > 
> > > need to use __PAGE_OFFSET instead of PAGE_OFFSET in the TASK_SIZE
> > > definition to escape the explicit unsigned long cast.  This just works
> > > because __PAGE_OFFSET is defined using _AC itself and thus never needs
> > > the cast anyway.
> > 
> > Shouldn't this be folded into the prior patch so there's no bisection
> > problem?
> 
> I didn't see a problem bisecting, do you have something particular in
> mind?

Oh, I misunderstood this patch to be a fix for compilation. Is this just
a correctness fix?

-- 
Kees Cook