kasan: introduce kasan_get_alloc_track

Add a kasan_get_alloc_track() helper that fetches alloc_track for a slab
object and use this helper in the common reporting code.

For now, the implementations of this helper are the same for the Generic
and tag-based modes, but they will diverge later in the series.

This change hides references to alloc_meta from the common reporting code.
This is desired as only the Generic mode will be using per-object
metadata after this series.

Link: https://lkml.kernel.org/r/0c365a35f4a833fff46f9d42c3212b32f7166556.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 13 insertions, 1 deletions

diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 98c451a3b01f..f212b9ae57b5 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -381,8 +381,20 @@ void kasan_save_free_info(struct kmem_cache *cache,
 	*(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREETRACK;
 }
 
+struct kasan_track *kasan_get_alloc_track(struct kmem_cache *cache,
+						void *object)
+{
+	struct kasan_alloc_meta *alloc_meta;
+
+	alloc_meta = kasan_get_alloc_meta(cache, object);
+	if (!alloc_meta)
+		return NULL;
+
+	return &alloc_meta->alloc_track;
+}
+
 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
-				void *object, u8 tag)
+						void *object, u8 tag)
 {
 	if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_SLAB_FREETRACK)
 		return NULL;