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

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Message-ID: <56A70C9D.8060102@oracle.com>
Date:	Tue, 26 Jan 2016 01:05:17 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Laura Abbott <labbott@...oraproject.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Michal Hocko <mhocko@...e.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	kernel-hardening@...ts.openwall.com,
	Kees Cook <keescook@...omium.org>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>
Subject: Re: [RFC][PATCH 0/3] Sanitization of buddy pages

On 01/25/2016 11:55 AM, Laura Abbott 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@...nda>)
> 
> 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
> 
> 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
> 

Should poisoning of this kind be using kasan rather than "old fashioned"
poisoning?


Thanks,
Sasha