The patch titled
Subject: mm/slab: expand CONFIG_SLAB_FREELIST_HARDENED to include SLAB
has been added to the -mm tree. Its filename is
mm-expand-config_slab_freelist_hardened-to-include-slab.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-expand-config_slab_freelist_hardened-to-include-slab.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-expand-config_slab_freelist_hardened-to-include-slab.patch
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------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: mm/slab: expand CONFIG_SLAB_FREELIST_HARDENED to include SLAB
Patch series "mm: Expand CONFIG_SLAB_FREELIST_HARDENED to include SLAB"
In reviewing Vlastimil Babka's latest slub debug series, I realized[1]
that several checks under CONFIG_SLAB_FREELIST_HARDENED weren't being
applied to SLAB. Fix this by expanding the Kconfig coverage, and adding a
simple double-free test for SLAB.
This patch (of 2):
Include SLAB caches when performing kmem_cache pointer verification. A
defense against such corruption[1] should be applied to all the
allocators. With this added, the "SLAB_FREE_CROSS" and "SLAB_FREE_PAGE"
LKDTM tests now pass on SLAB:
lkdtm: Performing direct entry SLAB_FREE_CROSS
lkdtm: Attempting cross-cache slab free ...
------------[ cut here ]------------
cache_from_obj: Wrong slab cache. lkdtm-heap-b but object is from lkdtm-heap-a
WARNING: CPU: 2 PID: 2195 at mm/slab.h:530 kmem_cache_free+0x8d/0x1d0
...
lkdtm: Performing direct entry SLAB_FREE_PAGE
lkdtm: Attempting non-Slab slab free ...
------------[ cut here ]------------
virt_to_cache: Object is not a Slab page!
WARNING: CPU: 1 PID: 2202 at mm/slab.h:489 kmem_cache_free+0x196/0x1d0
Additionally clean up neighboring Kconfig entries for clarity,
readability, and redundant option removal.
[1] https://github.com/ThomasKing2014/slides/raw/master/Building%20universal%20Android%20rooting%20with%20a%20type%20confusion%20vulnerability.pdf
Link: http://lkml.kernel.org/r/20200625215548.389774-1-keescook@xxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20200625215548.389774-2-keescook@xxxxxxxxxxxx
Fixes: 598a0717a816 ("mm/slab: validate cache membership under freelist hardening")
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Alexander Popov <alex.popov@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx>
Cc: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
init/Kconfig | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/init/Kconfig~mm-expand-config_slab_freelist_hardened-to-include-slab
+++ a/init/Kconfig
@@ -1885,9 +1885,8 @@ config SLAB_MERGE_DEFAULT
command line.
config SLAB_FREELIST_RANDOM
- default n
+ bool "Randomize slab freelist"
depends on SLAB || SLUB
- bool "SLAB freelist randomization"
help
Randomizes the freelist order used on creating new pages. This
security feature reduces the predictability of the kernel slab
@@ -1895,12 +1894,14 @@ config SLAB_FREELIST_RANDOM
config SLAB_FREELIST_HARDENED
bool "Harden slab freelist metadata"
- depends on SLUB
+ depends on SLAB || SLUB
help
Many kernel heap attacks try to target slab cache metadata and
other infrastructure. This options makes minor performance
sacrifices to harden the kernel slab allocator against common
- freelist exploit methods.
+ freelist exploit methods. Some slab implementations have more
+ sanity-checking than others. This option is most effective with
+ CONFIG_SLUB.
config SHUFFLE_PAGE_ALLOCATOR
bool "Page allocator randomization"
_
Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are
mm-expand-config_slab_freelist_hardened-to-include-slab.patch
slab-add-naive-detection-of-double-free.patch
exec-change-uselib2-is_sreg-failure-to-eacces.patch
exec-move-s_isreg-check-earlier.patch
exec-move-path_noexec-check-earlier.patch
