From patchwork Tue Sep 1 15:09:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 310533 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 C88CFC433E2 for ; Tue, 1 Sep 2020 15:23:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9BBCE2078B for ; Tue, 1 Sep 2020 15:23:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598973782; bh=tS6wCFBnmInIhbJdhLXjodAbxNXaMdJe2JzSqhoA64U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=E5JGz4KqezvgEioB/keGjoy8QjyXulTkD1nI9/f+cZ2F5K+JeszWM+3d8ATCeBmpR 5bkXoWQBLUYrQ5YaEHkeNH0JZnr3Gc/+IKt8HoNsliNrYkrKF7F/T0hQgZNwx1wOrT owIwQfXYOfDvHQTkGyEKXaTdEpY1lZzMmQ1xVBTQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729622AbgIAPXB (ORCPT ); Tue, 1 Sep 2020 11:23:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:45496 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728556AbgIAPXA (ORCPT ); Tue, 1 Sep 2020 11:23:00 -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 695612078B; Tue, 1 Sep 2020 15:22:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598973779; bh=tS6wCFBnmInIhbJdhLXjodAbxNXaMdJe2JzSqhoA64U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=guTZE8QlwJI7JRXmp85+ClvB/8N3bHDEB/dQru6pOJqbvCExVGPsx4aB/aFO4OhVA mEM3yGENbj5XuRH94xv/lqzCLSebXHWpnRxWspNS4gRudt4Wa6RDE1615hWs8oL+7f UzvG5UbG+J1kb+KJyJSzWUwOXEYXYxSuYC3wreGA= 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 4.19 044/125] ceph: fix potential mdsc use-after-free crash Date: Tue, 1 Sep 2020 17:09:59 +0200 Message-Id: <20200901150936.724649920@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901150934.576210879@linuxfoundation.org> References: <20200901150934.576210879@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 0fa14d8b9c64c..5f3707a90e7f7 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -3615,6 +3615,9 @@ 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 + @@ -3950,7 +3953,16 @@ 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);