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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 731D4C433E6 for ; Tue, 1 Sep 2020 17:11:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 410FA206FA for ; Tue, 1 Sep 2020 17:11:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598980279; bh=JcKkK6SjWJoKNYSJyFxdo3JBVP64FhLpgWA1lDUivaU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=KyvKaUOsoZuTh12dHOaO4xYyrHZz4yHfNkDcrUpJ6sQuEKPDcYbSl7/5YHfMRZ4sn 7/+UdPgiDKIxA7toUoUIeOhT17gTw9NIwAbYT4aS/en4JiIkV2hdqgUzxp9JC6XgQN 0Q7us3LOvXudC4BOzzNPsLegBRRkg4eBtW2TRAJc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729194AbgIARLR (ORCPT ); Tue, 1 Sep 2020 13:11:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:33148 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728826AbgIAPQ1 (ORCPT ); Tue, 1 Sep 2020 11:16:27 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 35FFE206EB; Tue, 1 Sep 2020 15:16:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598973386; bh=JcKkK6SjWJoKNYSJyFxdo3JBVP64FhLpgWA1lDUivaU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oI/3HZcRL+OxyuieevM9RH/2h87tzp+mvcPWZY3NSMshCGtdGav3mHYIz/Br/AKmU 5KCY9SgJOEc9jzJ1xaf5MX5m3ur4NjZD2CGKZRuorag0sG24O1l9rB2+3nUruzaV2H XVj5NE16f+fzf9yP7wEWoL5VTgFY2lHgZqvlZKE4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiubo Li , Jeff Layton , Ilya Dryomov , Sasha Levin Subject: [PATCH 4.9 30/78] ceph: fix potential mdsc use-after-free crash Date: Tue, 1 Sep 2020 17:10:06 +0200 Message-Id: <20200901150926.247880633@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901150924.680106554@linuxfoundation.org> References: <20200901150924.680106554@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xiubo Li [ Upstream commit fa9967734227b44acb1b6918033f9122dc7825b9 ] Make sure the delayed work stopped before releasing the resources. cancel_delayed_work_sync() will only guarantee that the work finishes executing if the work is already in the ->worklist. That means after the cancel_delayed_work_sync() returns, it will leave the work requeued if it was rearmed at the end. That can lead to a use after free once the work struct is freed. Fix it by flushing the delayed work instead of trying to cancel it, and ensure that the work doesn't rearm if the mdsc is stopping. URL: https://tracker.ceph.com/issues/46293 Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin --- fs/ceph/mds_client.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 3139fbd4c34e3..4ec5a109df82b 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -3386,6 +3386,9 @@ static void delayed_work(struct work_struct *work) dout("mdsc delayed_work\n"); ceph_check_delayed_caps(mdsc); + if (mdsc->stopping) + return; + mutex_lock(&mdsc->mutex); renew_interval = mdsc->mdsmap->m_session_timeout >> 2; renew_caps = time_after_eq(jiffies, HZ*renew_interval + @@ -3717,7 +3720,16 @@ void ceph_mdsc_force_umount(struct ceph_mds_client *mdsc) static void ceph_mdsc_stop(struct ceph_mds_client *mdsc) { dout("stop\n"); - cancel_delayed_work_sync(&mdsc->delayed_work); /* cancel timer */ + /* + * Make sure the delayed work stopped before releasing + * the resources. + * + * Because the cancel_delayed_work_sync() will only + * guarantee that the work finishes executing. But the + * delayed work will re-arm itself again after that. + */ + flush_delayed_work(&mdsc->delayed_work); + if (mdsc->mdsmap) ceph_mdsmap_destroy(mdsc->mdsmap); kfree(mdsc->sessions); -- 2.25.1