Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation

From	Kees Cook <keescook@chromium.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation
Date	2017-07-07 20:50 +0200
Message-ID	<u0Gud-7RY-3@gated-at.bofh.it> (permalink)
References	(4 earlier) <u0jei-gY-21@gated-at.bofh.it> <u0kal-RF-7@gated-at.bofh.it> <u0BXA-4Oh-23@gated-at.bofh.it> <u0ELM-6Is-11@gated-at.bofh.it> <u0EVs-71k-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Fri, Jul 7, 2017 at 10:06 AM, Christoph Lameter <cl@linux.com> wrote:
> On Fri, 7 Jul 2017, Kees Cook wrote:
>
>> If we also added a >0 offset, that would make things even less
>> deterministic. Though I wonder if it would make the performance impact
>> higher. The XOR patch right now is very light.
>
> There would be barely any performance impact if you keep the offset within
> a cacheline since most objects start on a cacheline boundary. The
> processor has to fetch the cacheline anyways.

Sure, this seems like a nice additional bit of hardening, even if
we're limited to a cacheline. I'd still want to protect the spray and
index attacks though (which the XOR method covers), but we can do
both. We should keep them distinct patches, though. If you'll Ack the
XOR patch, I can poke at adding offset randomization?

-Kees

-- 
Kees Cook
Pixel Security

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH v3] mm: Add SLUB free list pointer obfuscation Kees Cook <keescook@chromium.org> - 2017-07-06 02:30 +0200
  Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Christoph Lameter <cl@linux.com> - 2017-07-06 15:50 +0200
    Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Kees Cook <keescook@chromium.org> - 2017-07-06 17:50 +0200
      Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Christoph Lameter <cl@linux.com> - 2017-07-06 18:00 +0200
        Re: [kernel-hardening] Re: [PATCH v3] mm: Add SLUB free list  pointer obfuscation Daniel Micay <danielmicay@gmail.com> - 2017-07-06 18:20 +0200
        Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Rik van Riel <riel@redhat.com> - 2017-07-06 20:00 +0200
          Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Kees Cook <keescook@chromium.org> - 2017-07-06 21:00 +0200
            Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Christoph Lameter <cl@linux.com> - 2017-07-07 16:00 +0200
              Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Kees Cook <keescook@chromium.org> - 2017-07-07 19:00 +0200
                Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Christoph Lameter <cl@linux.com> - 2017-07-07 19:10 +0200
                Re: [PATCH v3] mm: Add SLUB free list pointer obfuscation Kees Cook <keescook@chromium.org> - 2017-07-07 20:50 +0200

csiph-web