linux-kernel - Re: [PATCH] mm-kasan-switch-slub-to-stackdepot-enable-memory-quarantine-for-slub-fix

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Date:	Fri, 15 Jul 2016 19:17:04 +0200
From:	Alexander Potapenko <glider@...gle.com>
To:	Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Dmitriy Vyukov <dvyukov@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	kasan-dev <kasan-dev@...glegroups.com>,
	Linux Memory Management List <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm-kasan-switch-slub-to-stackdepot-enable-memory-quarantine-for-slub-fix

On Fri, Jul 15, 2016 at 6:50 PM, Andrey Ryabinin
<aryabinin@...tuozzo.com> wrote:
> - Remove CONFIG_SLAB ifdefs. The code works just fine with both allocators.
> - Reset metada offsets if metadata doesn't fit. Otherwise kasan_metadata_size()
> will give us the wrong results.
>
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
Acked-by: Alexander Potapenko <glider@...gle.com>
> ---
>  mm/kasan/kasan.c | 17 +++++------------
>  1 file changed, 5 insertions(+), 12 deletions(-)
>
> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index d92a7a2..b6f99e8 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -372,9 +372,7 @@ void kasan_cache_create(struct kmem_cache *cache, size_t *size,
>                         unsigned long *flags)
>  {
>         int redzone_adjust;
> -#ifdef CONFIG_SLAB
>         int orig_size = *size;
> -#endif
>
>         /* Add alloc meta. */
>         cache->kasan_info.alloc_meta_offset = *size;
> @@ -392,25 +390,20 @@ void kasan_cache_create(struct kmem_cache *cache, size_t *size,
>         if (redzone_adjust > 0)
>                 *size += redzone_adjust;
>
> -#ifdef CONFIG_SLAB
> -       *size = min(KMALLOC_MAX_SIZE,
> -                   max(*size,
> -                       cache->object_size +
> -                       optimal_redzone(cache->object_size)));
> +       *size = min(KMALLOC_MAX_SIZE, max(*size, cache->object_size +
> +                                       optimal_redzone(cache->object_size)));
> +
>         /*
>          * If the metadata doesn't fit, don't enable KASAN at all.
>          */
>         if (*size <= cache->kasan_info.alloc_meta_offset ||
>                         *size <= cache->kasan_info.free_meta_offset) {
> +               cache->kasan_info.alloc_meta_offset = 0;
> +               cache->kasan_info.free_meta_offset = 0;
>                 *size = orig_size;
>                 return;
>         }
> -#else
> -       *size = max(*size,
> -                       cache->object_size +
> -                       optimal_redzone(cache->object_size));
>
> -#endif
>         *flags |= SLAB_KASAN;
>  }
>
> --
> 2.7.3
>



-- 
Alexander Potapenko
Software Engineer

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