linux-kernel - Re: [PATCH v2] kasan, slub: fix handling of kasan_slab

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Message-ID: <4e0eb106-1b1e-93ba-af4f-6714413422c3@virtuozzo.com>
Date:   Wed, 7 Mar 2018 15:36:59 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v2] kasan, slub: fix handling of kasan_slab_free hook



On 03/06/2018 09:18 PM, Andrey Konovalov wrote:
> The kasan_slab_free hook's return value denotes whether the reuse of a
> slab object must be delayed (e.g. when the object is put into memory
> qurantine).
> 
> The current way SLUB handles this hook is by ignoring its return value
> and hardcoding checks similar (but not exactly the same) to the ones
> performed in kasan_slab_free, which is prone to making mistakes.
> 
> The main difference between the hardcoded checks and the ones in
> kasan_slab_free is whether we want to perform a free in case when an
> invalid-free or a double-free was detected (we don't).
> 
> This patch changes the way SLUB handles this by:
> 1. taking into account the return value of kasan_slab_free for each of
>    the objects, that are being freed;
> 2. reconstructing the freelist of objects to exclude the ones, whose
>    reuse must be delayed.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> ---

Acked-by: Andrey Ryabinin <aryabinin@...tuozzo.com>