The patch titled
Subject: mm/kasan: get rid of ->state in struct kasan_alloc_meta
has been added to the -mm tree. Its filename is
mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Subject: mm/kasan: get rid of ->state in struct kasan_alloc_meta
The state of object currently tracked in two places - shadow memory,
and the ->state field in struct kasan_alloc_meta.
We can get rid of the latter. The will save us a little bit of memory.
Also, this allow us to move free stack into struct kasan_alloc_meta,
without increasing memory consumption. So now we should always know
when the last time the object was freed. This may be useful for
long delayed use-after-free bugs.
As a side effect this fixes following UBSAN warning:
UBSAN: Undefined behaviour in mm/kasan/quarantine.c:102:13
member access within misaligned address ffff88000d1efebc for type 'struct qlist_node'
which requires 8 byte alignment
Link: http://lkml.kernel.org/r/1470062715-14077-5-git-send-email-aryabinin@xxxxxxxxxxxxx
Reported-by: kernel test robot <xiaolong.ye@xxxxxxxxx>
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kasan.h | 3 +
mm/kasan/kasan.c | 63 ++++++++++++++++++----------------------
mm/kasan/kasan.h | 12 +------
mm/kasan/quarantine.c | 2 -
mm/kasan/report.c | 23 +++-----------
mm/slab.c | 4 +-
mm/slub.c | 1
7 files changed, 43 insertions(+), 65 deletions(-)
diff -puN include/linux/kasan.h~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta include/linux/kasan.h
--- a/include/linux/kasan.h~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta
+++ a/include/linux/kasan.h
@@ -56,6 +56,7 @@ void kasan_cache_destroy(struct kmem_cac
void kasan_poison_slab(struct page *page);
void kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
void kasan_poison_object_data(struct kmem_cache *cache, void *object);
+void kasan_init_slab_obj(struct kmem_cache *cache, const void *object);
void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
void kasan_kfree_large(const void *ptr);
@@ -102,6 +103,8 @@ static inline void kasan_unpoison_object
void *object) {}
static inline void kasan_poison_object_data(struct kmem_cache *cache,
void *object) {}
+static inline void kasan_init_slab_obj(struct kmem_cache *cache,
+ const void *object) {}
static inline void kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags) {}
static inline void kasan_kfree_large(const void *ptr) {}
diff -puN mm/kasan/kasan.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta mm/kasan/kasan.c
--- a/mm/kasan/kasan.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta
+++ a/mm/kasan/kasan.c
@@ -442,11 +442,6 @@ void kasan_poison_object_data(struct kme
kasan_poison_shadow(object,
round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
KASAN_KMALLOC_REDZONE);
- if (cache->flags & SLAB_KASAN) {
- struct kasan_alloc_meta *alloc_info =
- get_alloc_info(cache, object);
- alloc_info->state = KASAN_STATE_INIT;
- }
}
static inline int in_irqentry_text(unsigned long ptr)
@@ -510,6 +505,17 @@ struct kasan_free_meta *get_free_info(st
return (void *)object + cache->kasan_info.free_meta_offset;
}
+void kasan_init_slab_obj(struct kmem_cache *cache, const void *object)
+{
+ struct kasan_alloc_meta *alloc_info;
+
+ if (!(cache->flags & SLAB_KASAN))
+ return;
+
+ alloc_info = get_alloc_info(cache, object);
+ __memset(alloc_info, 0, sizeof(*alloc_info));
+}
+
void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
{
kasan_kmalloc(cache, object, cache->object_size, flags);
@@ -529,34 +535,27 @@ static void kasan_poison_slab_free(struc
bool kasan_slab_free(struct kmem_cache *cache, void *object)
{
+ s8 shadow_byte;
+
/* RCU slabs could be legally used after free within the RCU period */
if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
return false;
- if (likely(cache->flags & SLAB_KASAN)) {
- struct kasan_alloc_meta *alloc_info;
- struct kasan_free_meta *free_info;
-
- alloc_info = get_alloc_info(cache, object);
- free_info = get_free_info(cache, object);
-
- switch (alloc_info->state) {
- case KASAN_STATE_ALLOC:
- alloc_info->state = KASAN_STATE_QUARANTINE;
- set_track(&free_info->track, GFP_NOWAIT);
- kasan_poison_slab_free(cache, object);
- quarantine_put(free_info, cache);
- return true;
- case KASAN_STATE_QUARANTINE:
- case KASAN_STATE_FREE:
- pr_err("Double free");
- dump_stack();
- break;
- default:
- break;
- }
+ shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
+ if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) {
+ pr_err("Double free");
+ dump_stack();
+ return true;
}
- return false;
+
+ kasan_poison_slab_free(cache, object);
+
+ if (unlikely(!(cache->flags & SLAB_KASAN)))
+ return false;
+
+ set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT);
+ quarantine_put(get_free_info(cache, object), cache);
+ return true;
}
void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
@@ -579,13 +578,9 @@ void kasan_kmalloc(struct kmem_cache *ca
kasan_unpoison_shadow(object, size);
kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
KASAN_KMALLOC_REDZONE);
- if (cache->flags & SLAB_KASAN) {
- struct kasan_alloc_meta *alloc_info =
- get_alloc_info(cache, object);
- alloc_info->state = KASAN_STATE_ALLOC;
- set_track(&alloc_info->track, flags);
- }
+ if (cache->flags & SLAB_KASAN)
+ set_track(&get_alloc_info(cache, object)->alloc_track, flags);
}
EXPORT_SYMBOL(kasan_kmalloc);
diff -puN mm/kasan/kasan.h~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta mm/kasan/kasan.h
--- a/mm/kasan/kasan.h~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta
+++ a/mm/kasan/kasan.h
@@ -59,13 +59,6 @@ struct kasan_global {
* Structures to keep alloc and free tracks *
*/
-enum kasan_state {
- KASAN_STATE_INIT,
- KASAN_STATE_ALLOC,
- KASAN_STATE_QUARANTINE,
- KASAN_STATE_FREE
-};
-
#define KASAN_STACK_DEPTH 64
struct kasan_track {
@@ -74,8 +67,8 @@ struct kasan_track {
};
struct kasan_alloc_meta {
- struct kasan_track track;
- u32 state;
+ struct kasan_track alloc_track;
+ struct kasan_track free_track;
};
struct qlist_node {
@@ -86,7 +79,6 @@ struct kasan_free_meta {
* Otherwise it might be used for the allocator freelist.
*/
struct qlist_node quarantine_link;
- struct kasan_track track;
};
struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
diff -puN mm/kasan/quarantine.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta mm/kasan/quarantine.c
--- a/mm/kasan/quarantine.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta
+++ a/mm/kasan/quarantine.c
@@ -144,13 +144,11 @@ static void *qlink_to_object(struct qlis
static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
{
void *object = qlink_to_object(qlink, cache);
- struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
unsigned long flags;
if (IS_ENABLED(CONFIG_SLAB))
local_irq_save(flags);
- alloc_info->state = KASAN_STATE_FREE;
___cache_free(cache, object, _THIS_IP_);
if (IS_ENABLED(CONFIG_SLAB))
diff -puN mm/kasan/report.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta mm/kasan/report.c
--- a/mm/kasan/report.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta
+++ a/mm/kasan/report.c
@@ -133,7 +133,6 @@ static void kasan_object_err(struct kmem
void *object, char *unused_reason)
{
struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
- struct kasan_free_meta *free_info;
dump_stack();
pr_err("Object at %p, in cache %s size: %d\n", object, cache->name,
@@ -141,23 +140,11 @@ static void kasan_object_err(struct kmem
if (!(cache->flags & SLAB_KASAN))
return;
- switch (alloc_info->state) {
- case KASAN_STATE_INIT:
- pr_err("Object not allocated yet\n");
- break;
- case KASAN_STATE_ALLOC:
- pr_err("Allocation:\n");
- print_track(&alloc_info->track);
- break;
- case KASAN_STATE_FREE:
- case KASAN_STATE_QUARANTINE:
- free_info = get_free_info(cache, object);
- pr_err("Allocation:\n");
- print_track(&alloc_info->track);
- pr_err("Deallocation:\n");
- print_track(&free_info->track);
- break;
- }
+
+ pr_err("Allocated:\n");
+ print_track(&alloc_info->alloc_track);
+ pr_err("Freed:\n");
+ print_track(&alloc_info->free_track);
}
static void print_address_description(struct kasan_access_info *info)
diff -puN mm/slab.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta mm/slab.c
--- a/mm/slab.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta
+++ a/mm/slab.c
@@ -2604,9 +2604,11 @@ static void cache_init_objs(struct kmem_
}
for (i = 0; i < cachep->num; i++) {
+ objp = index_to_obj(cachep, page, i);
+ kasan_init_slab_obj(cachep, objp);
+
/* constructor could break poison info */
if (DEBUG == 0 && cachep->ctor) {
- objp = index_to_obj(cachep, page, i);
kasan_unpoison_object_data(cachep, objp);
cachep->ctor(objp);
kasan_poison_object_data(cachep, objp);
diff -puN mm/slub.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta mm/slub.c
--- a/mm/slub.c~mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta
+++ a/mm/slub.c
@@ -1384,6 +1384,7 @@ static void setup_object(struct kmem_cac
void *object)
{
setup_object_debug(s, page, object);
+ kasan_init_slab_obj(s, object);
if (unlikely(s->ctor)) {
kasan_unpoison_object_data(s, object);
s->ctor(object);
_
Patches currently in -mm which might be from aryabinin@xxxxxxxxxxxxx are
mm-kasan-fix-corruptions-and-false-positive-reports.patch
mm-kasan-dont-reduce-quarantine-in-atomic-contexts.patch
mm-kasan-slub-dont-disable-interrupts-when-object-leaves-quarantine.patch
mm-kasan-get-rid-of-alloc_size-in-struct-kasan_alloc_meta.patch
mm-kasan-get-rid-of-state-in-struct-kasan_alloc_meta.patch
kasan-improve-double-free-reports.patch
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