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 the
data at 'orig_size' offset of 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. But it could cause trouble for other usage in future.
Use the existing kfence helper kfence_ksize() which can return the
real original request size.
Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
---
mm/slub.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/slub.c b/mm/slub.c
index af9a80071fe0..1d348899f7a3 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -768,6 +768,9 @@ static inline unsigned int get_orig_size(struct kmem_cache *s, void *object)
{
void *p = kasan_reset_tag(object);
+ if (is_kfence_address(object))
+ return kfence_ksize(object);
+
if (!slub_debug_orig_size(s))
return s->object_size;
--
2.27.0
