[0/3] mm/slab: Improved sanity checking

Message

Kees Cook May 30, 2019, 4:50 a.m. UTC

Hi,

This adds defenses against slab cache confusion (as seen in real-world
exploits[1]) and gracefully handles type confusions when trying to look
up slab caches from an arbitrary page. (Also is patch 3: new LKDTM tests
for these defenses as well as for the existing double-free detection. To
avoid possible merge conflicts, I'd prefer patch 3 went via drivers/misc,
which I will send to Greg separately, but I've included it here to help
illustrate the issues.)

-Kees

[1] https://github.com/ThomasKing2014/slides/raw/master/Building%20universal%20Android%20rooting%20with%20a%20type%20confusion%20vulnerability.pdf

Kees Cook (3):
  mm/slab: Validate cache membership under freelist hardening
  mm/slab: Sanity-check page type when looking up cache
  lkdtm/heap: Add tests for freelist hardening

 drivers/misc/lkdtm/core.c  |  5 +++
 drivers/misc/lkdtm/heap.c  | 72 ++++++++++++++++++++++++++++++++++++++
 drivers/misc/lkdtm/lkdtm.h |  5 +++
 mm/slab.c                  | 14 ++++----
 mm/slab.h                  | 29 +++++++++------
 5 files changed, 107 insertions(+), 18 deletions(-)