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

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Message-ID: <d632571d-43cb-9dec-a51f-7cf8a6f91c0b@virtuozzo.com>
Date:   Fri, 2 Dec 2016 17:45:18 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Josh Poimboeuf <jpoimboe@...hat.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 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...

> +
> +	kasan_unpoison_shadow(base, watermark - base);
>  }
>  
>  /*
>