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Date: Thu, 21 Sep 2017 11:04:35 -0500 (CDT)
From: Christopher Lameter <cl@...ux.com>
To: Kees Cook <keescook@...omium.org>
cc: LKML <linux-kernel@...r.kernel.org>, David Windsor <dave@...lcore.net>, 
    Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>, 
    Joonsoo Kim <iamjoonsoo.kim@....com>, 
    Andrew Morton <akpm@...ux-foundation.org>, Linux-MM <linux-mm@...ck.org>, 
    linux-xfs@...r.kernel.org, 
    "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>, 
    Network Development <netdev@...r.kernel.org>, 
    "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: Re: Re: [PATCH v3 03/31] usercopy: Mark kmalloc
 caches as usercopy caches

On Thu, 21 Sep 2017, Kees Cook wrote:

> > So what is the point of this patch?
>
> The DMA kmalloc caches are not whitelisted:

The DMA kmalloc caches are pretty obsolete and mostly there for obscure
drivers.

??

> >>                         kmalloc_dma_caches[i] = create_kmalloc_cache(n,
> >> -                               size, SLAB_CACHE_DMA | flags);
> >> +                               size, SLAB_CACHE_DMA | flags, 0, 0);
>
> So this is creating the distinction between the kmallocs that go to
> userspace and those that don't. The expectation is that future work
> can start to distinguish between "for userspace" and "only kernel"
> kmalloc allocations, as is already done here for DMA.

The creation of the kmalloc caches in earlier patches already setup the
"whitelisting". Why do it twice?

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