linux-kernel - [PATCH 5.14 102/169] mm, slub: fix potential use-after-free in slab_debugfs

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Date:   Mon, 25 Oct 2021 21:14:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miaohe Lin <linmiaohe@...wei.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Bharata B Rao <bharata@...ux.ibm.com>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Faiyaz Mohammed <faiyazm@...eaurora.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Pekka Enberg <penberg@...nel.org>,
        Roman Gushchin <guro@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.14 102/169] mm, slub: fix potential use-after-free in slab_debugfs_fops

From: Miaohe Lin <linmiaohe@...wei.com>

commit 67823a544414def2a36c212abadb55b23bcda00c upstream.

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@...wei.com>
Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrey Konovalov <andreyknvl@...il.com>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc: Bharata B Rao <bharata@...ux.ibm.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Faiyaz Mohammed <faiyazm@...eaurora.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Pekka Enberg <penberg@...nel.org>
Cc: Roman Gushchin <guro@...com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 mm/slub.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4604,13 +4604,15 @@ 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)