Re: [PATCH v4] x86/suspend: fix false positive KASAN warning on suspend/resume

Pavel Machek
2016-12-02T21:09:06Z

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On Fri 2016-12-02 11:42:21, Josh Poimboeuf wrote:
> Resuming from a suspend operation is showing a KASAN false positive
> warning:
>
>
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

Acked-by: Pavel Machek <pavel@ucw.cz>

> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index 0e9505f..b2a0cff 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 & ~(THREAD_SIZE - 1));
> +
> + kasan_unpoison_shadow(base, watermark - base);
> }
>

I know you modified this code to be arch-independend... but is it
really? I guess it is portable enough across architectures that run
kasan today..
Pavel
--
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