From 67823a544414def2a36c212abadb55b23bcda00c Mon Sep 17 00:00:00 2001
From: Miaohe Lin <linmiaohe@huawei.com>
Date: Mon, 18 Oct 2021 15:16:02 -0700
Subject: [PATCH] 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 <vbabka@suse.cz>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/slub.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index bf1793f..f3df0f0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4887,13 +4887,15 @@ int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
 		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)
-- 
2.7.4