From: Miaohe Lin <linmiaohe@xxxxxxxxxx> commit 899447f669da76cc3605665e1a95ee877bc464cc upstream. If object's reuse is delayed, it will be excluded from the reconstructed freelist. But we forgot to adjust the cnt accordingly. So there will be a mismatch between reconstructed freelist depth and cnt. This will lead to free_debug_processing() complaining about freelist count or a incorrect slub inuse count. Link: https://lkml.kernel.org/r/20210916123920.48704-3-linmiaohe@xxxxxxxxxx Fixes: c3895391df38 ("kasan, slub: fix handling of kasan_slab_free hook") Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Cc: Bharata B Rao <bharata@xxxxxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Faiyaz Mohammed <faiyazm@xxxxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/mm/slub.c +++ b/mm/slub.c @@ -1543,7 +1543,8 @@ static __always_inline bool slab_free_ho } static inline bool slab_free_freelist_hook(struct kmem_cache *s, - void **head, void **tail) + void **head, void **tail, + int *cnt) { void *object; @@ -1578,6 +1579,12 @@ static inline bool slab_free_freelist_ho *head = object; if (!*tail) *tail = object; + } else { + /* + * Adjust the reconstructed freelist depth + * accordingly if object's reuse is delayed. + */ + --(*cnt); } } while (object != old_tail); @@ -3137,7 +3144,7 @@ static __always_inline void slab_free(st * With KASAN enabled slab_free_freelist_hook modifies the freelist * to remove objects, whose reuse must be delayed. */ - if (slab_free_freelist_hook(s, &head, &tail)) + if (slab_free_freelist_hook(s, &head, &tail, &cnt)) do_slab_free(s, page, head, tail, cnt, addr); }
