From: Marco Elver <elver@google.com>
To: elver@google.com, akpm@linux-foundation.org, glider@google.com
Cc: hpa@zytor.com, paulmck@kernel.org, andreyknvl@google.com,
aryabinin@virtuozzo.com, luto@kernel.org, bp@alien8.de,
catalin.marinas@arm.com, cl@linux.com,
dave.hansen@linux.intel.com, rientjes@google.com,
dvyukov@google.com, edumazet@google.com,
gregkh@linuxfoundation.org, hdanton@sina.com, mingo@redhat.com,
jannh@google.com, Jonathan.Cameron@huawei.com, corbet@lwn.net,
iamjoonsoo.kim@lge.com, joern@purestorage.com,
keescook@chromium.org, mark.rutland@arm.com, penberg@kernel.org,
peterz@infradead.org, sjpark@amazon.com, tglx@linutronix.de,
vbabka@suse.cz, will@kernel.org, x86@kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org,
linux-mm@kvack.org
Subject: [PATCH v6 6/9] kfence, kasan: make KFENCE compatible with KASAN
Date: Thu, 29 Oct 2020 14:16:46 +0100 [thread overview]
Message-ID: <20201029131649.182037-7-elver@google.com> (raw)
In-Reply-To: <20201029131649.182037-1-elver@google.com>
From: Alexander Potapenko <glider@google.com>
We make KFENCE compatible with KASAN for testing KFENCE itself. In
particular, KASAN helps to catch any potential corruptions to KFENCE
state, or other corruptions that may be a result of freepointer
corruptions in the main allocators.
To indicate that the combination of the two is generally discouraged,
CONFIG_EXPERT=y should be set. It also gives us the nice property that
KFENCE will be build-tested by allyesconfig builds.
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Co-developed-by: Marco Elver <elver@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
---
v5:
* Also guard kasan_unpoison_shadow with is_kfence_address(), as it may
be called from SL*B internals, currently ksize().
* Make kasan_record_aux_stack() compatible with KFENCE, which may be
called from outside KASAN runtime.
---
lib/Kconfig.kfence | 2 +-
mm/kasan/common.c | 15 +++++++++++++++
mm/kasan/generic.c | 3 ++-
3 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/lib/Kconfig.kfence b/lib/Kconfig.kfence
index d24baa3bce4a..639b48cc75d4 100644
--- a/lib/Kconfig.kfence
+++ b/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 && (!KASAN || EXPERT) && (SLAB || SLUB)
depends on JUMP_LABEL # To ensure performance, require jump labels
select STACKTRACE
help
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 950fd372a07e..ac1d404fb41e 100644
--- a/mm/kasan/common.c
+++ b/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>
@@ -141,6 +142,14 @@ void kasan_unpoison_shadow(const void *address, size_t size)
*/
address = reset_tag(address);
+ /*
+ * We may be called from SL*B internals, such as ksize(): with a size
+ * not a multiple of machine-word size, avoid poisoning the invalid
+ * portion of the word for KFENCE memory.
+ */
+ if (is_kfence_address(address))
+ return;
+
kasan_poison_shadow(address, size, tag);
if (size & KASAN_SHADOW_MASK) {
@@ -396,6 +405,9 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
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 +456,9 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
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,
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 248264b9cb76..1069ecd1cd55 100644
--- a/mm/kasan/generic.c
+++ b/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;
--
2.29.1.341.ge80a0c044ae-goog
next prev parent reply other threads:[~2020-10-29 13:17 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-29 13:16 [PATCH v6 0/9] KFENCE: A low-overhead sampling-based memory safety error detector Marco Elver
2020-10-29 13:16 ` [PATCH v6 1/9] mm: add Kernel Electric-Fence infrastructure Marco Elver
2020-10-30 2:49 ` Jann Horn
2020-10-30 19:16 ` Marco Elver
2020-10-29 13:16 ` [PATCH v6 2/9] x86, kfence: enable KFENCE for x86 Marco Elver
2020-10-30 2:49 ` Jann Horn
2020-10-30 13:00 ` Marco Elver
2020-10-30 15:22 ` Jann Horn
2020-10-29 13:16 ` [PATCH v6 3/9] arm64, kfence: enable KFENCE for ARM64 Marco Elver
2020-10-30 2:49 ` Jann Horn
2020-10-30 16:00 ` Mark Rutland
2020-10-30 15:47 ` Mark Rutland
2020-10-30 15:54 ` Marco Elver
2020-10-29 13:16 ` [PATCH v6 4/9] mm, kfence: insert KFENCE hooks for SLAB Marco Elver
2020-10-30 2:49 ` Jann Horn
2020-10-30 15:41 ` Marco Elver
2020-10-29 13:16 ` [PATCH v6 5/9] mm, kfence: insert KFENCE hooks for SLUB Marco Elver
2020-10-30 2:49 ` Jann Horn
2020-10-29 13:16 ` Marco Elver [this message]
2020-10-30 2:49 ` [PATCH v6 6/9] kfence, kasan: make KFENCE compatible with KASAN Jann Horn
2020-10-30 13:46 ` Marco Elver
2020-10-30 15:08 ` Jann Horn
2020-10-30 15:19 ` Marco Elver
2020-10-29 13:16 ` [PATCH v6 7/9] kfence, Documentation: add KFENCE documentation Marco Elver
2020-10-30 2:49 ` Jann Horn
2020-10-30 9:59 ` Alexander Potapenko
2020-10-29 13:16 ` [PATCH v6 8/9] kfence: add test suite Marco Elver
2020-10-30 2:49 ` Jann Horn
2020-10-30 10:50 ` Marco Elver
2020-10-29 13:16 ` [PATCH v6 9/9] MAINTAINERS: Add entry for KFENCE Marco Elver
2020-10-30 2:50 ` Jann Horn
2020-10-30 2:49 ` [PATCH v6 0/9] KFENCE: A low-overhead sampling-based memory safety error detector Jann Horn
2020-10-30 10:56 ` Marco Elver
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