[PATCH mm] kfence, slab: fix cache_alloc_debugcheck_after() for bulk allocations

Marco Elver
2021-03-04T20:53:04Z

cache_alloc_debugcheck_after() performs checks on an object, including
adjusting the returned pointer. None of this should apply to KFENCE
objects. While for non-bulk allocations, the checks are skipped when we
allocate via KFENCE, for bulk allocations cache_alloc_debugcheck_after()
is called via cache_alloc_debugcheck_after_bulk().

Fix it by skipping cache_alloc_debugcheck_after() for KFENCE objects.

Signed-off-by: Marco Elver <elver@google.com>
---
mm/slab.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slab.c b/mm/slab.c
index 51fd424e0d6d..ae651bf540b7 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2992,7 +2992,7 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
gfp_t flags, void *objp, unsigned long caller)
{
WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
- if (!objp)
+ if (!objp || is_kfence_address(objp))
return objp;
if (cachep->flags & SLAB_POISON) {
check_poison_obj(cachep, objp);
--
2.30.1.766.gb4fecdf3b7-goog