Re: [kernel-hardening] [RFC][PATCH 6/7] mm: Add Kconfig option for slab sanitization

Christoph Lameter
2015-12-22T16:25:00Z

On Tue, 22 Dec 2015, Dave Hansen wrote:

> On 12/21/2015 07:40 PM, Laura Abbott wrote:
> > + The tradeoff is performance impact. The noticible impact can vary
> > + and you are advised to test this feature on your expected workload
> > + before deploying it
>
> What if instead of writing SLAB_MEMORY_SANITIZE_VALUE, we wrote 0's?
> That still destroys the information, but it has the positive effect of
> allowing a kzalloc() call to avoid zeroing the slab object. It might
> mitigate some of the performance impact.

We already write zeros in many cases or the object is initialized in a
different. No one really wants an uninitialized object. The problem may be
that a freed object is having its old content until reused. Which is
something that poisoning deals with.