The patch titled
Subject: kfence, kasan: make KFENCE compatible with KASAN
has been added to the -mm tree. Its filename is
kfence-kasan-make-kfence-compatible-with-kasan.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kfence-kasan-make-kfence-compatible-with-kasan.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kfence-kasan-make-kfence-compatible-with-kasan.patch
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------------------------------------------------------
From: Alexander Potapenko <glider@xxxxxxxxxx>
Subject: kfence, kasan: make KFENCE compatible with KASAN
Make KFENCE compatible with KASAN. Currently this helps test KFENCE
itself, where KASAN can catch potential corruptions to KFENCE state, or
other corruptions that may be a result of freepointer corruptions in the
main allocators.
Link: https://lkml.kernel.org/r/20201103175841.3495947-7-elver@xxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Reviewed-by: Jann Horn <jannh@xxxxxxxxxx>
Co-developed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christopher Lameter <cl@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Joern Engel <joern@xxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: SeongJae Park <sjpark@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/Kconfig.kfence | 2 +-
mm/kasan/common.c | 19 +++++++++++++++++++
mm/kasan/generic.c | 3 ++-
3 files changed, 22 insertions(+), 2 deletions(-)
--- a/lib/Kconfig.kfence~kfence-kasan-make-kfence-compatible-with-kasan
+++ a/lib/Kconfig.kfence
@@ -5,7 +5,7 @@ config HAVE_ARCH_KFENCE
menuconfig KFENCE
bool "KFENCE: low-overhead sampling-based memory safety error detector"
- depends on HAVE_ARCH_KFENCE && !KASAN && (SLAB || SLUB)
+ depends on HAVE_ARCH_KFENCE && (SLAB || SLUB)
depends on JUMP_LABEL # To ensure performance, require jump labels
select STACKTRACE
help
--- a/mm/kasan/common.c~kfence-kasan-make-kfence-compatible-with-kasan
+++ a/mm/kasan/common.c
@@ -18,6 +18,7 @@
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
+#include <linux/kfence.h>
#include <linux/kmemleak.h>
#include <linux/linkage.h>
#include <linux/memblock.h>
@@ -124,6 +125,10 @@ void kasan_poison_shadow(const void *add
*/
address = reset_tag(address);
+ /* Skip KFENCE memory if called explicitly outside of sl*b. */
+ if (is_kfence_address(address))
+ return;
+
shadow_start = kasan_mem_to_shadow(address);
shadow_end = kasan_mem_to_shadow(address + size);
@@ -141,6 +146,14 @@ void kasan_unpoison_shadow(const void *a
*/
address = reset_tag(address);
+ /*
+ * Skip KFENCE memory if called explicitly outside of sl*b. Also note
+ * that calls to ksize(), where size is not a multiple of machine-word
+ * size, would otherwise poison the invalid portion of the word.
+ */
+ if (is_kfence_address(address))
+ return;
+
kasan_poison_shadow(address, size, tag);
if (size & KASAN_SHADOW_MASK) {
@@ -396,6 +409,9 @@ static bool __kasan_slab_free(struct kme
tagged_object = object;
object = reset_tag(object);
+ if (is_kfence_address(object))
+ return false;
+
if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
object)) {
kasan_report_invalid_free(tagged_object, ip);
@@ -444,6 +460,9 @@ static void *__kasan_kmalloc(struct kmem
if (unlikely(object == NULL))
return NULL;
+ if (is_kfence_address(object))
+ return (void *)object;
+
redzone_start = round_up((unsigned long)(object + size),
KASAN_SHADOW_SCALE_SIZE);
redzone_end = round_up((unsigned long)object + cache->object_size,
--- a/mm/kasan/generic.c~kfence-kasan-make-kfence-compatible-with-kasan
+++ a/mm/kasan/generic.c
@@ -21,6 +21,7 @@
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
+#include <linux/kfence.h>
#include <linux/kmemleak.h>
#include <linux/linkage.h>
#include <linux/memblock.h>
@@ -332,7 +333,7 @@ void kasan_record_aux_stack(void *addr)
struct kasan_alloc_meta *alloc_info;
void *object;
- if (!(page && PageSlab(page)))
+ if (is_kfence_address(addr) || !(page && PageSlab(page)))
return;
cache = page->slab_cache;
_
Patches currently in -mm which might be from glider@xxxxxxxxxx are
mm-add-kernel-electric-fence-infrastructure.patch
x86-kfence-enable-kfence-for-x86.patch
mm-kfence-insert-kfence-hooks-for-slab.patch
mm-kfence-insert-kfence-hooks-for-slub.patch
kfence-kasan-make-kfence-compatible-with-kasan.patch
