[PATCH 2/5] mm/slub: Consider kfence case for get_orig_size()

[Feng Tang]

When 'orig_size' of kmalloc object is enabled by debug option, it
should either contains the actual requested size or the cache's
'object_size'.

But it's not true if that object is a kfence-allocated one, and its
'orig_size' in metadata could be zero or other values. This is not
a big issue for current 'orig_size' usage, as init_object() and
check_object() during alloc/free process will be skipped for kfence
addresses.

As 'orig_size' will be used by some function block like krealloc(),
handle it by returning the 'object_size' in get_orig_size() for
kfence addresses.

Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
---
 mm/slub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 996a72fa6f62..4cb3822dba08 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -768,7 +768,7 @@ static inline unsigned int get_orig_size(struct kmem_cache *s, void *object)
 {
 	void *p = kasan_reset_tag(object);
 
-	if (!slub_debug_orig_size(s))
+	if (!slub_debug_orig_size(s) || is_kfence_address(object))
 		return s->object_size;
 
 	p += get_info_end(s);
-- 
2.34.1