From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1CEB2C07E9D for ; Thu, 22 Jul 2021 04:03:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0827608FC for ; Thu, 22 Jul 2021 04:03:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231195AbhGVDXN (ORCPT ); Wed, 21 Jul 2021 23:23:13 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:11462 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231238AbhGVDWl (ORCPT ); Wed, 21 Jul 2021 23:22:41 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GVdxz559Jzch9T; Thu, 22 Jul 2021 11:59:51 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 22 Jul 2021 12:03:15 +0800 Received: from thunder-town.china.huawei.com (10.174.179.0) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 22 Jul 2021 12:03:14 +0800 From: Zhen Lei To: Ilya Dryomov , Dongsheng Yang , Jens Axboe , Yehuda Sadeh , Sage Weil , ceph-devel , linux-block , linux-kernel CC: Zhen Lei Subject: [PATCH] rbd: use kref_put_lock() to fix potential UAF Date: Thu, 22 Jul 2021 12:02:16 +0800 Message-ID: <20210722040216.4090-1-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.174.179.0] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org When the refcount is decreased to 0, the rbd_client_release() is called. Before CPU0 reaches the race point (1), CPU1 may obtain the spinlock and traverse the linked list to find 'rbdc'. Although CPU1 will call kref_get() to increase the refcount, it is obviously too late. CPU0 will release 'rbdc' directly, CPU1 then accesses 'rbdc' and triggers UAF. Use kref_put_lock() to ensure that both the operations of decrease refcount to 0 and link deletion are lock protected eliminates this risk. CPU0 CPU1 rbd_client_release(): <-------- (1) spin_lock(&rbd_client_list_lock); list_del(&rbdc->node); spin_unlock(&rbd_client_list_lock); kfree(rbdc); <-------- use-after-free Fixes: 602adf400201 ("rbd: introduce rados block device (rbd), based on libceph") Signed-off-by: Zhen Lei --- drivers/block/rbd.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 531d390902dd..3a8989bf8e9c 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -875,11 +875,11 @@ static void rbd_client_release(struct kref *kref) { struct rbd_client *rbdc = container_of(kref, struct rbd_client, kref); - dout("%s: rbdc %p\n", __func__, rbdc); - spin_lock(&rbd_client_list_lock); list_del(&rbdc->node); spin_unlock(&rbd_client_list_lock); + dout("%s: rbdc %p\n", __func__, rbdc); + ceph_destroy_client(rbdc->client); kfree(rbdc); } @@ -891,7 +891,8 @@ static void rbd_client_release(struct kref *kref) static void rbd_put_client(struct rbd_client *rbdc) { if (rbdc) - kref_put(&rbdc->kref, rbd_client_release); + kref_put_lock(&rbdc->kref, + rbd_client_release, &rbd_client_list_lock); } /* -- 2.25.1