linux-kernel - Re: [PATCH v3] x86/suspend: fix false positive KASAN warning on suspend/resume

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Message-ID: <20161202150819.2h25oyoj7qsvrw77@treble>
Date:   Fri, 2 Dec 2016 09:08:19 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        linux-pm@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andy Lutomirski <luto@...capital.net>,
        Scott Bauer <scott.bauer@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        Alexander Potapenko <glider@...gle.com>,
        kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [PATCH v3] x86/suspend: fix false positive KASAN warning on
 suspend/resume

On Fri, Dec 02, 2016 at 05:45:18PM +0300, Andrey Ryabinin wrote:
> 
> 
> On 12/02/2016 05:42 PM, Josh Poimboeuf wrote:
> 
> 
> > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> > index 0e9505f..e9d8ba0 100644
> > --- a/mm/kasan/kasan.c
> > +++ b/mm/kasan/kasan.c
> > @@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
> >  /* Unpoison the stack for the current task beyond a watermark sp value. */
> >  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
> >  {
> > -	__kasan_unpoison_stack(current, watermark);
> > +	/*
> > +	 * Calculate the task stack base address.  Avoid using 'current'
> > +	 * because this function is called by early resume code which hasn't
> > +	 * yet set up the percpu register (%gs).
> > +	 */
> > +	void *base = (void *)((unsigned long)watermark & CURRENT_MASK);
> 
> CURRENT_MASK is defined only on x86...

Oops.  I guess I should have taken your suggested patch verbatim...

Will do a proper multi-arch compile before submitting v4.

-- 
Josh