linux-kernel - Re: [PATCH v2 2/3] mm/slub: Fix redzoning for small allocations

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Message-ID: <202010121342.836D3C26CF@keescook>
Date:   Mon, 12 Oct 2020 13:43:31 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christopher Lameter <cl@...ux.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, stable@...r.kernel.org,
        Marco Elver <elver@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>, Roman Gushchin <guro@...com>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v2 2/3] mm/slub: Fix redzoning for small allocations

On Mon, Oct 12, 2020 at 08:01:04AM +0000, Christopher Lameter wrote:
> On Fri, 9 Oct 2020, Kees Cook wrote:
> 
> > Store the freelist pointer out of line when object_size is smaller than
> > sizeof(void *) and redzoning is enabled.
> >
> > (Note that no caches with such a size are known to exist in the kernel
> > currently.)
> 
> Ummm... The smallest allowable cache size is sizeof(void *) as I recall.
> 
> 
> mm/slab_common.c::kmem_sanity_check() checks the sizes when caches are
> created.

Ah thank you! Yes, I really thought there was a place where that
happened, but I missed it. This patch can be dropped.

-- 
Kees Cook