[PATCH 4.4-cip 0/5] Faster page poisoning for security

Ben Hutchings <ben.hutchings@...>

This is a backport of changes in 4.6 to add new config options to page
poisoning. Page poisoning was originally intended a debug feature for
finding use-after-free bugs in the kernel, but it can also be a security
feature, mitigating the security impact of such bugs. Unfortunately, it
normally has a significant performance cost. The new options
enabled to reduce the performance cost, though they also reduce the
likelihood of detecting when such a bug has been triggered.

Enable CONFIG_PAGE_POISONING plus the new options can make some such
bugs harder to exploit, at a small performance cost (you'll need to
measure it yourself).

For this and other backports, I'm looking for feedback like:
- Did I miss a follow-up fix or an earlier dependency?
- Does this cause a regression (other than as explained above)?
- Are you likely to use it?
- Are there related features you want in 4.4?


Joonsoo Kim (3):
mm/slab: activate debug_pagealloc in SLAB when it is actually enabled
mm/slab: use more appropriate condition check for debug_pagealloc
mm/slab: clean up DEBUG_PAGEALLOC processing code

Laura Abbott (2):
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 | 23 ++++++--
include/linux/poison.h | 4 ++
kernel/power/hibernate.c | 17 ++++++
mm/Kconfig.debug | 39 ++++++++++++-
mm/Makefile | 2 +-
mm/page_alloc.c | 13 ++++-
mm/page_ext.c | 10 +++-
mm/{debug-pagealloc.c => page_poison.c} | 67 +++++++++++++++++-----
mm/slab.c | 98 +++++++++++++++++----------------
10 files changed, 208 insertions(+), 70 deletions(-)
rename mm/{debug-pagealloc.c => page_poison.c} (64%)


Ben Hutchings
Software Developer, Codethink Ltd.