| From: |
| Anisse Astier <anisse@astier.eu> |
| To: |
| unlisted-recipients:; (no To-header on input) |
| Subject: |
| [PATCH 0/2] Sanitizing freed pages |
| Date: |
| Fri, 24 Apr 2015 23:05:47 +0200 |
| Message-ID: |
| <1429909549-11726-1-git-send-email-anisse@astier.eu> |
| Cc: |
| Anisse Astier <anisse@astier.eu>, Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@suse.de>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, David Rientjes <rientjes@google.com>, Alan Cox <gnomes@lxorguk.ukuu.org.uk>, Linus Torvalds <torvalds@linux-foundation.org>, Peter Zijlstra <peterz@infradead.org>, PaX Team <pageexec@freemail.hu>, Brad Spengler <spender@grsecurity.net>, Kees Cook <keescook@chromium.org>, linux-mm@kvack.org, linux-kernel@vger.kernel.org |
| Archive‑link: | |
Article |
Hi,
I'm trying revive an old debate here[1], though with a simpler approach than
was previously tried. This patch series implements a new option to sanitize
freed pages, a (very) small subset of what is done in PaX/grsecurity[3],
inspired by a previous submission [4].
The first patch is fairly independent, and could be taken as-is. The second is
the meat and should be straight-forward to review.
There are a few different uses that this can cover:
- some cases of use-after-free could be detected (crashes), although this not
as efficient as KAsan/kmemcheck
- it can help with long-term memory consumption in an environment with
multiple VMs and Kernel Same-page Merging on the host. [2]
- finally, it can reduce infoleaks, although this is hard to measure.
The approach is voluntarily kept as simple as possible. A single configuration
option, no command line option, no sysctl nob. It can of course be changed,
although I'd be wary of runtime-configuration options that could be used for
races.
I haven't been able to measure a meaningful performance difference when
compiling a (in-cache) kernel; I'd be interested to see what difference it
makes with your particular workload/hardware (I suspect mine is CPU-bound on
this small laptop).
[1] https://lwn.net/Articles/334747/
[2] https://staff.aist.go.jp/k.suzaki/EuroSec12-SUZAKI-revise...
[3] http://en.wikibooks.org/wiki/Grsecurity/Appendix/Grsecuri...
[4] http://article.gmane.org/gmane.linux.kernel.mm/34398
Anisse Astier (2):
mm/page_alloc.c: cleanup obsolete KM_USER*
mm/page_alloc.c: add config option to sanitize freed pages
mm/Kconfig | 12 ++++++++++++
mm/page_alloc.c | 15 +++++++--------
2 files changed, 19 insertions(+), 8 deletions(-)
--
1.9.3
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