[PATCH v2 03/21] KASAN: remove code paths guarded by CONFIG_SLAB

Vlastimil Babka
2023-11-20T18:34:42Z

With SLAB removed and SLUB the only remaining allocator, we can clean up
some code that was depending on the choice.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/kasan/common.c | 13 ++-----------
mm/kasan/kasan.h | 3 +--
mm/kasan/quarantine.c | 7 -------
3 files changed, 3 insertions(+), 20 deletions(-)

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 256930da578a..5d95219e69d7 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -153,10 +153,6 @@ void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
* 2. A cache might be SLAB_TYPESAFE_BY_RCU, which means objects can be
* accessed after being freed. We preassign tags for objects in these
* caches as well.
- * 3. For SLAB allocator we can't preassign tags randomly since the freelist
- * is stored as an array of indexes instead of a linked list. Assign tags
- * based on objects indexes, so that objects that are next to each other
- * get different tags.
*/
static inline u8 assign_tag(struct kmem_cache *cache,
const void *object, bool init)
@@ -171,17 +167,12 @@ static inline u8 assign_tag(struct kmem_cache *cache,
if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU))
return init ? KASAN_TAG_KERNEL : kasan_random_tag();

- /* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */
-#ifdef CONFIG_SLAB
- /* For SLAB assign tags based on the object index in the freelist. */
- return (u8)obj_to_index(cache, virt_to_slab(object), (void *)object);
-#else
/*
- * For SLUB assign a random tag during slab creation, otherwise reuse
+ * For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU,
+ * assign a random tag during slab creation, otherwise reuse
* the already assigned tag.
*/
return init ? kasan_random_tag() : get_tag(object);
-#endif
}

void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 8b06bab5c406..eef50233640a 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -373,8 +373,7 @@ void kasan_set_track(struct kasan_track *track, gfp_t flags);
void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags);
void kasan_save_free_info(struct kmem_cache *cache, void *object);

-#if defined(CONFIG_KASAN_GENERIC) && \
- (defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
+#ifdef CONFIG_KASAN_GENERIC
bool kasan_quarantine_put(struct kmem_cache *cache, void *object);
void kasan_quarantine_reduce(void);
void kasan_quarantine_remove_cache(struct kmem_cache *cache);
diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index ca4529156735..138c57b836f2 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -144,10 +144,6 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
{
void *object = qlink_to_object(qlink, cache);
struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);
- unsigned long flags;
-
- if (IS_ENABLED(CONFIG_SLAB))
- local_irq_save(flags);

/*
* If init_on_free is enabled and KASAN's free metadata is stored in
@@ -166,9 +162,6 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
*(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREE;

___cache_free(cache, object, _THIS_IP_);
-
- if (IS_ENABLED(CONFIG_SLAB))
- local_irq_restore(flags);
}

static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache)

--
2.42.1