linux-kernel - Re: [PATCH 2/4] x86: convert threshold_bank.cpus from atomic_t to refcount

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Message-ID: <20170222092638.GA9953@nazgul.tnic>
Date:   Wed, 22 Feb 2017 10:27:48 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Kees Cook <keescook@...omium.org>
Cc:     Elena Reshetova <elena.reshetova@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-edac@...r.kernel.org,
        "x86@...nel.org" <x86@...nel.org>,
        sparclinux <sparclinux@...r.kernel.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        KVM <kvm@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Tony Luck <tony.luck@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Hans Liljestrand <ishkamiel@...il.com>,
        David Windsor <dwindsor@...il.com>
Subject: Re: [PATCH 2/4] x86: convert threshold_bank.cpus from atomic_t to
 refcount_t

On Tue, Feb 21, 2017 at 12:45:30PM -0800, Kees Cook wrote:
> On Mon, Feb 20, 2017 at 3:17 AM, Borislav Petkov <bp@...en8.de> wrote:
> > On Mon, Feb 20, 2017 at 01:06:19PM +0200, Elena Reshetova wrote:
> >> refcount_t type and corresponding API should be
> >> used instead of atomic_t when the variable is used as
> >> a reference counter. This allows to avoid accidental
> >> refcounter overflows that might lead to use-after-free
> >> situations.
> >>
> >> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> >> Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
> >> Signed-off-by: Kees Cook <keescook@...omium.org>
> >> Signed-off-by: David Windsor <dwindsor@...il.com>
> >
> > That SOB chain tells me that you wrote the patch and Hans, Kees and
> > David handled it in some way and the last one - David - is sending it to
> > me. It doesn't look like that though.
> 
> Perhaps the least inaccurate form of this might be:
> 
> 
> Inspired by atomic protections in PaX/grsecurity.
> 
> Suggested-by: Kees Cook <keescook@...omium.org>
> Reviewed-by: David Windsor <dwindsor@...il.com>
> Reviewed-by: Hans Liljestrand <ishkamiel@...il.com>
> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> 
> 
> As this is something I'd suggested we implement based on the work in
> PaX/grsecurity, David took the first (and continuing) stab at
> conversions, Hans did more, and Elena has been doing even more along
> with the heavy-lifting of keeping the series organized. That way the
> first SoB is still the author, the last SoB is still the email sender,
> and everyone's name is mentioned.
> 
> Or just:
> 
> 
> Inspired by atomic protections in PaX/grsecurity, based on work from
> David Windsor, Hans Liljestrand, and myself.
> 
> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> 
> 
> I'm not picky -- I just want to see the conversion to refcount_t

Me neither - both look good to me and actually explain what the SOB
chain was trying to say.

Thanks!

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--