From nobody Mon Apr 20 01:11:38 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 93B62CCA481 for ; Wed, 29 Jun 2022 07:24:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231858AbiF2HYP (ORCPT ); Wed, 29 Jun 2022 03:24:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231775AbiF2HYI (ORCPT ); Wed, 29 Jun 2022 03:24:08 -0400 Received: from mail-m971.mail.163.com (mail-m971.mail.163.com [123.126.97.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3891B1928E for ; Wed, 29 Jun 2022 00:24:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=krvw6 qwr/IZNtIPW1oz/T//NVChJsEDf0J7wBQxN9uo=; b=ifrxMVQy2hSFHVZnDqlcU a0bNEtGYsLueeADGVR+YCCDTxYJvCpdmGo3UJKNpKyzrg83tzf6z+D36NK5HcSrv YXaOF0z1Tf0cLLGdM484sieT2yi5nZmNGCHeBCLew0l9XblYlc4uLLN7Ob7LdJri BxvwGblQhUiXUrkjmJJZ+E= Received: from localhost.localdomain (unknown [123.112.69.106]) by smtp1 (Coremail) with SMTP id GdxpCgCXgqPW_btiXNRwLg--.54145S4; Wed, 29 Jun 2022 15:23:47 +0800 (CST) From: Jianglei Nie To: dan.j.williams@intel.com, vishal.l.verma@intel.com, dave.jiang@intel.com, fenghua.yu@intel.com, ravi.v.shankar@intel.com Cc: nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, Jianglei Nie Subject: [PATCH] =?UTF-8?q?=EF=BB=BFdax:=20Fix=20potential=20uaf=20in=20?= =?UTF-8?q?=5F=5Fdax=5Fpmem=5Fprobe()?= Date: Wed, 29 Jun 2022 15:22:59 +0800 Message-Id: <20220629072259.2150978-1-niejianglei2021@163.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: GdxpCgCXgqPW_btiXNRwLg--.54145S4 X-Coremail-Antispam: 1Uf129KBjvJXoW7CFykXrWktw4rKw18CFyxAFb_yoW8ZF18p3 y5XFyUurWDAr1Uur43Aws3uFyrZa1ktw4rCr4xuw47u345Z34xA3y8Xa4jya47K3yxAr1U X3Wjqw1xu3y7uF7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0zRIks9UUUUU= X-Originating-IP: [123.112.69.106] X-CM-SenderInfo: xqlhyxxdqjzvrlsqjii6rwjhhfrp/1tbiFQMvjF5mLh+DBgAAs5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" __dax_pmem_probe() allocates a memory chunk from dax_region with alloc_dax_region(). alloc_dax_region() increases the refcount for dax_region and uses devm_add_action_or_reset() to make the parent dev manage the dax_region. The dax_region will be used if the parent dev is destroyed. Then the function calls devm_create_dev_dax() to make child dev_dax instances own the lifetime of the dax_region. devm_create_dev_dax() calls devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev); to make the child dev_dax manage the dax_region and register the destroy function "unregister_dev_dax".The devm_create_dev_dax() increases the refcount for dax_region when the function is successfully executed. But when some error occurs, devm_create_dev_dax() may return ERR_PTR before increasing the refcount for dax_region. In these cases, the call for dax_region_put() will decrease the ref count for dax_region and trigger dax_region_free(), which will execute kfree(dax_region). When the parent dev is destroyed, the registered destroy function "unregister_dev_dax" will be triggered and calls dax_region_free(), which will use the freed dax_region, leading to a use after free bug. We should check the return value of devm_create_dev_dax(). If it returns ERR_PTR, we should return this function with ERR_PTR. Signed-off-by: Jianglei Nie Reported-by: kernel test robot --- drivers/dax/pmem.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index f050ea78bb83..d5c8bd546ee9 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -66,6 +66,8 @@ static struct dev_dax *__dax_pmem_probe(struct device *de= v) .size =3D range_len(&range), }; dev_dax =3D devm_create_dev_dax(&data); + if (IS_ERR(dev_dax)) + return ERR_PTR((dev_dax); =20 /* child dev_dax instances now own the lifetime of the dax_region */ dax_region_put(dax_region); --=20 2.25.1