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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 8B69FC2D0DB for ; Tue, 28 Jan 2020 14:48:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5B3B6207FD for ; Tue, 28 Jan 2020 14:48:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580222907; bh=jFBkBZpR37Xa506YkLZCDaF6CQW7L2QeG0BSlqy/7Fc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=GqjYe1RRXrclLqdlhR6lTqhjxEYh3SCYThT1vA84zECIDCZyZnR7L4I+iniOQsY1j j9WMvGMjaIe22Ekku+OPzCulfiUhtRuyLDgZh3fhg0JOs0/5DiKpSqDJuRHOBiC9cG BdzzPeBPQXJOmTMiOnF4Rj7TAlFkObDHrVLS4hqk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727260AbgA1Os0 (ORCPT ); Tue, 28 Jan 2020 09:48:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:48938 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726766AbgA1OCf (ORCPT ); Tue, 28 Jan 2020 09:02:35 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 0BA8024695; Tue, 28 Jan 2020 14:02:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580220154; bh=jFBkBZpR37Xa506YkLZCDaF6CQW7L2QeG0BSlqy/7Fc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0QFGBWnViUzI8nRODgViJUaF6nLzTpw6pnJDKAIe+DpTLoyQ3BUuEb/CObgtGti9Q UuRg2KxQJUzblwm87YL808+aKk9IN83bXHevd/QI/KvyzdzRPGL4FK/xKkMHL6Uf36 r9V7WLztZDMFAOG5c4XylOimKN/dmaWo1qC43264= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jeff Layton , "Yan, Zheng" , Ilya Dryomov Subject: [PATCH 5.4 037/104] ceph: hold extra reference to r_parent over life of request Date: Tue, 28 Jan 2020 14:59:58 +0100 Message-Id: <20200128135822.575355015@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200128135817.238524998@linuxfoundation.org> References: <20200128135817.238524998@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: Jeff Layton commit 9c1c2b35f1d94de8325344c2777d7ee67492db3b upstream. Currently, we just assume that it will stick around by virtue of the submitter's reference, but later patches will allow the syscall to return early and we can't rely on that reference at that point. While I'm not aware of any reports of it, Xiubo pointed out that this may fix a use-after-free. If the wait for a reply times out or is canceled via signal, and then the reply comes in after the syscall returns, the client can end up trying to access r_parent without a reference. Take an extra reference to the inode when setting r_parent and release it when releasing the request. Cc: stable@vger.kernel.org Signed-off-by: Jeff Layton Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman --- fs/ceph/mds_client.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -708,8 +708,10 @@ void ceph_mdsc_release_request(struct kr /* avoid calling iput_final() in mds dispatch threads */ ceph_async_iput(req->r_inode); } - if (req->r_parent) + if (req->r_parent) { ceph_put_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN); + ceph_async_iput(req->r_parent); + } ceph_async_iput(req->r_target_inode); if (req->r_dentry) dput(req->r_dentry); @@ -2670,8 +2672,10 @@ int ceph_mdsc_submit_request(struct ceph /* take CAP_PIN refs for r_inode, r_parent, r_old_dentry */ if (req->r_inode) ceph_get_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN); - if (req->r_parent) + if (req->r_parent) { ceph_get_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN); + ihold(req->r_parent); + } if (req->r_old_dentry_dir) ceph_get_cap_refs(ceph_inode(req->r_old_dentry_dir), CEPH_CAP_PIN);