Re: [kernel-hardening] Re: [PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches

[Christopher Lameter]

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?