From nobody Wed Apr 8 08:21:32 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9196C433FE for ; Sat, 12 Nov 2022 10:58:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234741AbiKLK62 (ORCPT ); Sat, 12 Nov 2022 05:58:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230170AbiKLK60 (ORCPT ); Sat, 12 Nov 2022 05:58:26 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A863DBC0C for ; Sat, 12 Nov 2022 02:58:22 -0800 (PST) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4N8Xbz2YFmzRp3V; Sat, 12 Nov 2022 18:58:07 +0800 (CST) Received: from dggpemm100009.china.huawei.com (7.185.36.113) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Sat, 12 Nov 2022 18:58:21 +0800 Received: from huawei.com (10.175.113.32) by dggpemm100009.china.huawei.com (7.185.36.113) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Sat, 12 Nov 2022 18:58:20 +0800 From: Liu Shixin To: Christoph Lameter , Pekka Enberg , "David Rientjes" , Joonsoo Kim , "Andrew Morton" , Vlastimil Babka , "Roman Gushchin" , Hyeonggon Yoo <42.hyeyoo@gmail.com> CC: , , Liu Shixin Subject: [PATCH v4 3/3] mm/slub: Fix memory leak of kobj->name in sysfs_slab_add() Date: Sat, 12 Nov 2022 19:46:02 +0800 Message-ID: <20221112114602.1268989-4-liushixin2@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221112114602.1268989-1-liushixin2@huawei.com> References: <20221112114602.1268989-1-liushixin2@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.113.32] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm100009.china.huawei.com (7.185.36.113) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" There is a memory leak of kobj->name in sysfs_slab_add(): unreferenced object 0xffff88817e446440 (size 32): comm "insmod", pid 4085, jiffies 4296564501 (age 126.272s) hex dump (first 32 bytes): 75 62 69 66 73 5f 69 6e 6f 64 65 5f 73 6c 61 62 ubifs_inode_slab 00 65 44 7e 81 88 ff ff 00 00 00 00 00 00 00 00 .eD~............ backtrace: [<000000005b30fbbd>] __kmalloc_node_track_caller+0x4e/0x150 [<000000002f70da0c>] kstrdup_const+0x4b/0x80 [<00000000c6712c61>] kobject_set_name_vargs+0x2f/0xb0 [<00000000b151218e>] kobject_init_and_add+0xb0/0x120 [<00000000e56a4cf5>] sysfs_slab_add+0x17d/0x220 [<000000009326fd57>] __kmem_cache_create+0x406/0x590 [<00000000dde33cff>] kmem_cache_create_usercopy+0x1fc/0x300 [<00000000fe90cedb>] kmem_cache_create+0x12/0x20 [<000000007a6531c8>] 0xffffffffa02d802d [<000000000e3b13c7>] do_one_initcall+0x87/0x2a0 [<00000000995ecdcf>] do_init_module+0xdf/0x320 [<000000008821941f>] load_module+0x2f98/0x3330 [<00000000ef51efa4>] __do_sys_finit_module+0x113/0x1b0 [<000000009339fbce>] do_syscall_64+0x35/0x80 [<000000006b7f2033>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 Following the rules stated in the comment for kobject_init_and_add(): If this function returns an error, kobject_put() must be called to properly clean up the memory associated with the object. kobject_put() is more appropriate for error handling after kobject_init(). And we can use this function to solve this problem. For the cache created early, the related sysfs_slab_add() is called in slab_sysfs_init(). Skip free these kmem_cache since they are important for system. Keep them working without sysfs. Fixes: 80da026a8e5d ("mm/slub: fix slab double-free in case of duplicate sy= sfs filename") Signed-off-by: Liu Shixin --- include/linux/slub_def.h | 4 ++-- mm/slab_common.c | 6 ++---- mm/slub.c | 21 +++++++++++++++++---- 3 files changed, 21 insertions(+), 10 deletions(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 26d56c4c74d1..90c3e06b77b1 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -144,11 +144,11 @@ struct kmem_cache { =20 #ifdef CONFIG_SYSFS #define SLAB_SUPPORTS_SYSFS -int sysfs_slab_add(struct kmem_cache *); +int sysfs_slab_add(struct kmem_cache *, bool); void sysfs_slab_unlink(struct kmem_cache *); void sysfs_slab_release(struct kmem_cache *); #else -static inline int sysfs_slab_add(struct kmem_cache *s) +static inline int sysfs_slab_add(struct kmem_cache *s, bool free_slab) { return 0; } diff --git a/mm/slab_common.c b/mm/slab_common.c index 55e2cf064dfe..30808a1d1b32 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -237,11 +237,9 @@ static struct kmem_cache *create_cache(const char *nam= e, #ifdef SLAB_SUPPORTS_SYSFS /* Mutex is not taken during early boot */ if (slab_state >=3D FULL) { - err =3D sysfs_slab_add(s); - if (err) { - slab_kmem_cache_release(s); + err =3D sysfs_slab_add(s, true); + if (err) return ERR_PTR(err); - } debugfs_slab_add(s); } #endif diff --git a/mm/slub.c b/mm/slub.c index a1ad759753ce..25575bce0c3c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5881,7 +5881,7 @@ static char *create_unique_id(struct kmem_cache *s) return name; } =20 -int sysfs_slab_add(struct kmem_cache *s) +int sysfs_slab_add(struct kmem_cache *s, bool free_slab) { int err; const char *name; @@ -5911,14 +5911,17 @@ int sysfs_slab_add(struct kmem_cache *s) * for the symlinks. */ name =3D create_unique_id(s); - if (IS_ERR(name)) + if (IS_ERR(name)) { + if (free_slab) + slab_kmem_cache_release(s); return PTR_ERR(name); + } } =20 s->kobj.kset =3D kset; err =3D kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); if (err) - goto out; + goto out_put_kobj; =20 err =3D sysfs_create_group(&s->kobj, &slab_attr_group); if (err) @@ -5934,6 +5937,16 @@ int sysfs_slab_add(struct kmem_cache *s) return err; out_del_kobj: kobject_del(&s->kobj); +out_put_kobj: + /* + * Skip free kmem_cache that create early since they are important + * for system. Keep them working without sysfs. Only free the name + * for early allocated kmem_cache. + */ + if (free_slab) + kobject_put(&s->kobj); + else + kfree_const(s->kobj.name); goto out; } =20 @@ -6002,7 +6015,7 @@ static int __init slab_sysfs_init(void) slab_state =3D FULL; =20 list_for_each_entry(s, &slab_caches, list) { - err =3D sysfs_slab_add(s); + err =3D sysfs_slab_add(s, false); if (err) pr_err("SLUB: Unable to add boot slab %s to sysfs\n", s->name); --=20 2.25.1