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@virtuozzo.com
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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);
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) {}
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)
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);
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;
+ 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;
+ }
- alloc_info = get_alloc_info(cache, object);
- free_info = get_free_info(cache, object);
+ kasan_poison_slab_free(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;
- }
- }
- return false;
+ 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,
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);
* 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 {
};
struct kasan_alloc_meta {
- struct kasan_track track;
- u32 state;
+ struct kasan_track alloc_track;
+ struct kasan_track free_track;
};
struct qlist_node {
* 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,
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))
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,
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)
}
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);
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);
projects / cascardo / linux.git / commitdiff