1 files changed, 42 insertions, 32 deletions

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 610efae91220..ed4873e18c75 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -55,7 +55,7 @@ void kasan_set_track(struct kasan_track *track, depot_stack_handle_t stack)
 	u64 ts_nsec = local_clock();
 
 	track->cpu = cpu;
-	track->timestamp = ts_nsec >> 3;
+	track->timestamp = ts_nsec >> 9;
 #endif /* CONFIG_KASAN_EXTRA_INFO */
 	track->pid = current->pid;
 	track->stack = stack;
@@ -65,8 +65,7 @@ void kasan_save_track(struct kasan_track *track, gfp_t flags)
 {
 	depot_stack_handle_t stack;
 
-	stack = kasan_save_stack(flags,
-			STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET);
+	stack = kasan_save_stack(flags, STACK_DEPOT_FLAG_CAN_ALLOC);
 	kasan_set_track(track, stack);
 }
 
@@ -209,15 +208,12 @@ void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
 	return (void *)object;
 }
 
-static inline bool poison_slab_object(struct kmem_cache *cache, void *object,
-				      unsigned long ip, bool init)
+/* Returns true when freeing the object is not safe. */
+static bool check_slab_allocation(struct kmem_cache *cache, void *object,
+				  unsigned long ip)
 {
-	void *tagged_object;
-
-	if (!kasan_arch_is_ready())
-		return false;
+	void *tagged_object = object;
 
-	tagged_object = object;
 	object = kasan_reset_tag(object);
 
 	if (unlikely(nearest_obj(cache, virt_to_slab(object), object) != object)) {
@@ -225,37 +221,47 @@ static inline bool poison_slab_object(struct kmem_cache *cache, void *object,
 		return true;
 	}
 
-	/* RCU slabs could be legally used after free within the RCU period. */
-	if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
-		return false;
-
 	if (!kasan_byte_accessible(tagged_object)) {
 		kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_DOUBLE_FREE);
 		return true;
 	}
 
+	return false;
+}
+
+static inline void poison_slab_object(struct kmem_cache *cache, void *object,
+				      bool init, bool still_accessible)
+{
+	void *tagged_object = object;
+
+	object = kasan_reset_tag(object);
+
+	/* RCU slabs could be legally used after free within the RCU period. */
+	if (unlikely(still_accessible))
+		return;
+
 	kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
 			KASAN_SLAB_FREE, init);
 
 	if (kasan_stack_collection_enabled())
 		kasan_save_free_info(cache, tagged_object);
+}
 
-	return false;
+bool __kasan_slab_pre_free(struct kmem_cache *cache, void *object,
+				unsigned long ip)
+{
+	if (!kasan_arch_is_ready() || is_kfence_address(object))
+		return false;
+	return check_slab_allocation(cache, object, ip);
 }
 
-bool __kasan_slab_free(struct kmem_cache *cache, void *object,
-				unsigned long ip, bool init)
+bool __kasan_slab_free(struct kmem_cache *cache, void *object, bool init,
+		       bool still_accessible)
 {
-	if (is_kfence_address(object))
+	if (!kasan_arch_is_ready() || is_kfence_address(object))
 		return false;
 
-	/*
-	 * If the object is buggy, do not let slab put the object onto the
-	 * freelist. The object will thus never be allocated again and its
-	 * metadata will never get released.
-	 */
-	if (poison_slab_object(cache, object, ip, init))
-		return true;
+	poison_slab_object(cache, object, init, still_accessible);
 
 	/*
 	 * If the object is put into quarantine, do not let slab put the object
@@ -266,10 +272,9 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object,
 		return true;
 
 	/*
-	 * If the object is not put into quarantine, it will likely be quickly
-	 * reallocated. Thus, release its metadata now.
+	 * Note: Keep per-object metadata to allow KASAN print stack traces for
+	 * use-after-free-before-realloc bugs.
 	 */
-	kasan_release_object_meta(cache, object);
 
 	/* Let slab put the object onto the freelist. */
 	return false;
@@ -506,11 +511,16 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip)
 		return true;
 	}
 
-	if (is_kfence_address(ptr))
-		return false;
+	if (is_kfence_address(ptr) || !kasan_arch_is_ready())
+		return true;
 
 	slab = folio_slab(folio);
-	return !poison_slab_object(slab->slab_cache, ptr, ip, false);
+
+	if (check_slab_allocation(slab->slab_cache, ptr, ip))
+		return false;
+
+	poison_slab_object(slab->slab_cache, ptr, false, false);
+	return true;
 }
 
 void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
@@ -534,7 +544,7 @@ void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
 		return;
 
 	/* Unpoison the object and save alloc info for non-kmalloc() allocations. */
-	unpoison_slab_object(slab->slab_cache, ptr, size, flags);
+	unpoison_slab_object(slab->slab_cache, ptr, flags, false);
 
 	/* Poison the redzone and save alloc info for kmalloc() allocations. */
 	if (is_kmalloc_cache(slab->slab_cache))