From nobody Tue Apr 7 12:47:40 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 5C930C433FE for ; Mon, 17 Oct 2022 12:40:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230268AbiJQMkQ (ORCPT ); Mon, 17 Oct 2022 08:40:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229562AbiJQMkM (ORCPT ); Mon, 17 Oct 2022 08:40:12 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9570437FB5 for ; Mon, 17 Oct 2022 05:40:09 -0700 (PDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Mrbdr2j5zzHv2K; Mon, 17 Oct 2022 20:19:28 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 17 Oct 2022 20:19:29 +0800 Received: from huawei.com (10.175.103.91) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 17 Oct 2022 20:19:29 +0800 From: Yang Yingliang To: CC: , Subject: [PATCH v2] class: fix possible memory leak in __class_register() Date: Mon, 17 Oct 2022 20:18:55 +0800 Message-ID: <20221017121855.67335-1-yangyingliang@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.103.91] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Inject fault while probing module (e.g. pktcdvd.ko), kset_register() may fail in __class_register(), if it fails, but the refcount of kobject is not decreased to 0, the name allocated in kobject_set_name() is leaked. To fix this by calling kfree_const(). unreferenced object 0xffff888102fa8190 (size 8): comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s) hex dump (first 8 bytes): 70 6b 74 63 64 76 64 00 pktcdvd. backtrace: [<00000000e7c7703d>] __kmalloc_track_caller+0x1ae/0x320 [<000000005e4d70bc>] kstrdup+0x3a/0x70 [<00000000c2e5e85a>] kstrdup_const+0x68/0x80 [<000000000049a8c7>] kvasprintf_const+0x10b/0x190 [<0000000029123163>] kobject_set_name_vargs+0x56/0x150 [<00000000747219c9>] kobject_set_name+0xab/0xe0 [<0000000005f1ea4e>] __class_register+0x15c/0x49a If class_add_groups() fails, it need delete kobject and free its name, besides, subsys_private also need be freed. unreferenced object 0xffff888037274000 (size 1024): comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s) hex dump (first 32 bytes): 00 40 27 37 80 88 ff ff 00 40 27 37 80 88 ff ff .@'7.....@'7.... 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... backtrace: [<00000000151f9600>] kmem_cache_alloc_trace+0x17c/0x2f0 [<00000000ecf3dd95>] __class_register+0x86/0x49a It can not call kset_put() or kset_unregister() in error path, because the 'cls' will be freed in callback function class_release() and it also freed in error path, it will cause double free. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Yang Yingliang --- v1 -> v2: Update commit message and add fix tag. --- drivers/base/class.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/base/class.c b/drivers/base/class.c index 64f7b9a0970f..87de0a04ee9b 100644 --- a/drivers/base/class.c +++ b/drivers/base/class.c @@ -187,11 +187,17 @@ int __class_register(struct class *cls, struct lock_c= lass_key *key) =20 error =3D kset_register(&cp->subsys); if (error) { + kfree_const(cp->subsys.kobj.name); kfree(cp); return error; } error =3D class_add_groups(class_get(cls), cls->class_groups); class_put(cls); + if (error) { + kobject_del(&cp->subsys.kobj); + kfree_const(cp->subsys.kobj.name); + kfree(cp); + } return error; } EXPORT_SYMBOL_GPL(__class_register); --=20 2.25.1