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 E1A5EC433E2 for ; Tue, 1 Sep 2020 17:19:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1395207D3 for ; Tue, 1 Sep 2020 17:19:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598980771; bh=fjmDARNuO3p8EyzzMXvS56Vf8PfN9ySp3dmgUpJE0JM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zLTf2D/sRk0WiouS8bWrbeqysj9CL1m3EnAt9Gk3uC8NDoGudxlfaTAd6HJWGh9pT s9w4tr7qsEGsJy1Unqv83zYbxX9tS5qKOpSBl78gFgPhCFlvBVKYUEV5Hf0XwcRWFs diqdLCYUTHh9Pe3yJE4i9ZXa2JWKZGANy7k3s7I0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732594AbgIART3 (ORCPT ); Tue, 1 Sep 2020 13:19:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:56960 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728953AbgIAPNm (ORCPT ); Tue, 1 Sep 2020 11:13:42 -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 944012078B; Tue, 1 Sep 2020 15:13:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598973222; bh=fjmDARNuO3p8EyzzMXvS56Vf8PfN9ySp3dmgUpJE0JM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=plhGvfKXxQR8UontRaPPHBxp8tyTEMq/L6DqB/vbnUgEJbzLC47wICx0JIgPpVH6h 7vrAGIMkCL/PVunJ1dxEPOVLW+FhzbVtcVfubMqbm/YRKY4kCzuydrXW/vesUvGMy6 9pXhAr3EI0FBT0e4F1GYj6bixsOmSakuUfM2h7S4= 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 4.4 26/62] ceph: fix potential mdsc use-after-free crash Date: Tue, 1 Sep 2020 17:10:09 +0200 Message-Id: <20200901150922.039102547@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901150920.697676718@linuxfoundation.org> References: <20200901150920.697676718@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 a5de8e22629ba..b7fd7d69be075 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -3428,6 +3428,9 @@ 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 + @@ -3752,7 +3755,16 @@ 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