Re: [kernel-hardening] [RFC][PATCH 0/3] Sanitization of buddy pages

[Mathias Krause]

On 25 January 2016 at 17:55, Laura Abbott <labbott@xxxxxxxxxxxxxxxxx> wrote:
> Hi,
>
> This is an implementation of page poisoning/sanitization for all arches. It
> takes advantage of the existing implementation for
> !ARCH_SUPPORTS_DEBUG_PAGEALLOC arches. This is a different approach than what
> the Grsecurity patches were taking but should provide equivalent functionality.
>
> For those who aren't familiar with this, the goal of sanitization is to reduce
> the severity of use after free and uninitialized data bugs. Memory is cleared
> on free so any sensitive data is no longer available. Discussion of
> sanitization was brough up in a thread about CVEs
> (lkml.kernel.org/g/<20160119112812.GA10818@mwanda>)
>
> I eventually expect Kconfig names will want to be changed and or moved if this
> is going to be used for security but that can happen later.
>
> Credit to Mathias Krause for the version in grsecurity

Thanks for the credits but I don't deserve them. I've contributed the
slab based sanitization only. The page based one shipped in PaX and
grsecurity is from the PaX Team.

>
> Laura Abbott (3):
>   mm/debug-pagealloc.c: Split out page poisoning from debug page_alloc
>   mm/page_poison.c: Enable PAGE_POISONING as a separate option
>   mm/page_poisoning.c: Allow for zero poisoning
>
>  Documentation/kernel-parameters.txt |   5 ++
>  include/linux/mm.h                  |  13 +++
>  include/linux/poison.h              |   4 +
>  mm/Kconfig.debug                    |  35 +++++++-
>  mm/Makefile                         |   5 +-
>  mm/debug-pagealloc.c                | 127 +----------------------------
>  mm/page_alloc.c                     |  10 ++-
>  mm/page_poison.c                    | 158 ++++++++++++++++++++++++++++++++++++
>  8 files changed, 228 insertions(+), 129 deletions(-)
>  create mode 100644 mm/page_poison.c
>
> --
> 2.5.0
>

Regards,
Mathias