mm/slab: rerform init_on_free earlier

Currently in CONFIG_SLAB init_on_free happens too late, and heap objects
go to the heap quarantine not being erased.

Lets move init_on_free clearing before calling kasan_slab_free().  In that
case heap quarantine will store erased objects, similarly to CONFIG_SLUB=y
behavior.

Link: https://lkml.kernel.org/r/20201210183729.1261524-1-alex.popov@linux.com
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/slab.c b/mm/slab.c
index 2e67a51..176b65e 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3417,6 +3417,9 @@ free_done:
 static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
                                         unsigned long caller)
 {
+       if (unlikely(slab_want_init_on_free(cachep)))
+               memset(objp, 0, cachep->object_size);
+
        /* Put the object into the quarantine, don't touch it for now. */
        if (kasan_slab_free(cachep, objp, _RET_IP_))
                return;
@@ -3435,8 +3438,6 @@ void ___cache_free(struct kmem_cache *cachep, void *objp,
        struct array_cache *ac = cpu_cache_get(cachep);
 
        check_irq_off();
-       if (unlikely(slab_want_init_on_free(cachep)))
-               memset(objp, 0, cachep->object_size);
        kmemleak_free_recursive(objp, cachep->flags);
        objp = cache_free_debugcheck(cachep, objp, caller);
        memcg_slab_free_hook(cachep, &objp, 1);