linux-kernel - [PATCH 4/5] mm, slub: fix potential use-after-free in slab_debugfs

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Message-ID: <20210916123920.48704-5-linmiaohe@huawei.com>
Date:   Thu, 16 Sep 2021 20:39:19 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <cl@...ux.com>, <penberg@...nel.org>,
        <rientjes@...gle.com>, <iamjoonsoo.kim@....com>, <vbabka@...e.cz>
CC:     <gregkh@...uxfoundation.org>, <faiyazm@...eaurora.org>,
        <andreyknvl@...il.com>, <ryabinin.a.a@...il.com>,
        <thgarnie@...gle.com>, <keescook@...omium.org>,
        <bharata@...ux.ibm.com>, <guro@...com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH 4/5] 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.

Fixes: 64dd68497be7 ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/slub.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index bf1793fb4ce5..f3df0f04a472 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)
-- 
2.23.0