[patch 13/19] mm, slub: fix potential use-after-free in slab_debugfs_fops

From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm, slub: fix potential use-after-free in slab_debugfs_fops

When sysfs_slab_add failed, we shouldn't call debugfs_slab_add() for s
because s will be freed soon.  And slab_debugfs_fops will use s later
leading to a use-after-free.

Link: https://lkml.kernel.org/r/20210916123920.48704-5-linmiaohe@huawei.com
Fixes: 64dd68497be7 ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <redacted>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <redacted>
Cc: Christoph Lameter <redacted>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <redacted>
Cc: Kees Cook <redacted>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <redacted>
Cc: <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/slub.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/slub.c~mm-slub-fix-potential-use-after-free-in-slab_debugfs_fops
+++ a/mm/slub.c

@@ -4887,13 +4887,15 @@ int __kmem_cache_create(struct kmem_cach
 		return 0;
 
 	err = sysfs_slab_add(s);
-	if (err)
+	if (err) {
 		__kmem_cache_release(s);
+		return err;
+	}
 
 	if (s->flags & SLAB_STORE_USER)
 		debugfs_slab_add(s);
 
-	return err;
+	return 0;
 }
 
 void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller)

_