linux-kernel - [PATCH] slub: assign refcount for kmalloc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1356449082-3016-1-git-send-email-js1304@gmail.com>
Date:	Wed, 26 Dec 2012 00:24:42 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	Paul Hargrove <phhargrove@....gov>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Joonsoo Kim <js1304@...il.com>,
	Christoph Lameter <cl@...ux.com>
Subject: [PATCH] slub: assign refcount for kmalloc_caches

commit cce89f4f6911286500cf7be0363f46c9b0a12ce0('Move kmem_cache
refcounting to common code') moves some refcount manipulation code to
common code. Unfortunately, it also removed refcount assignment for
kmalloc_caches. So, kmalloc_caches's refcount is initially 0.
This makes errornous situation.

Paul Hargrove report that when he create a 8-byte kmem_cache and
destory it, he encounter below message.
'Objects remaining in kmalloc-8 on kmem_cache_close()'

8-byte kmem_cache merge with 8-byte kmalloc cache and refcount is
increased by one. So, resulting refcount is 1. When destory it, it hit
refcount = 0, then kmem_cache_close() is executed and error message is
printed.

This patch assign initial refcount 1 to kmalloc_caches, so fix this
errornous situtation.

Cc: <stable@...r.kernel.org> # v3.7
Cc: Christoph Lameter <cl@...ux.com>
Reported-by: Paul Hargrove <phhargrove@....gov>
Signed-off-by: Joonsoo Kim <js1304@...il.com>

diff --git a/mm/slub.c b/mm/slub.c
index a0d6984..321afab 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3279,6 +3279,7 @@ static struct kmem_cache *__init create_kmalloc_cache(const char *name,
 	if (kmem_cache_open(s, flags))
 		goto panic;

+	s->refcount = 1;
 	list_add(&s->list, &slab_caches);
 	return s;

-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/