linux-kernel - Re: [PATCH] locking/atomics: don't alias ___

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 28 Jun 2017 14:24:50 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Dmitry Vyukov <dvyukov@...gle.com>
cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will.deacon@....com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        "x86@...nel.org" <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] locking/atomics: don't alias ____ptr

On Wed, 28 Jun 2017, Dmitry Vyukov wrote:
> On Wed, Jun 28, 2017 at 1:10 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> >  #define cmpxchg_local(ptr, old, new)                   \
> >  ({                                                     \
> > -       __typeof__(ptr) ____ptr = (ptr);                \
> > -       kasan_check_write(____ptr, sizeof(*____ptr));   \
> > -       arch_cmpxchg_local(____ptr, (old), (new));      \
> > +       kasan_check_write((ptr), sizeof(*(ptr)));       \
> > +       arch_cmpxchg_local((ptr), (old), (new));        \
> 
> 
> /\/\/\/\/\/\/\/\/\/\/\/\
> 
> These are macros.
> If ptr is foo(), then we will call foo() twice.

If that's true, the foo() will be evaluated a gazillion more times down the
way to the end of this macro maze.

Thanks,

	tglx