From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933900AbdERNhI convert rfc822-to-8bit (ORCPT ); Thu, 18 May 2017 09:37:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45784 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932445AbdERNgy (ORCPT ); Thu, 18 May 2017 09:36:54 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 06C423DBC9 Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=zyan@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 06C423DBC9 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [PATCH] ceph: check i_nlink while converting a file handle to dentry From: "Yan, Zheng" In-Reply-To: <20170517112107.31025-1-lhenriques@suse.com> Date: Thu, 18 May 2017 21:36:44 +0800 Cc: Sage Weil , Ilya Dryomov , ceph-devel , Linux Kernel Mailing List Content-Transfer-Encoding: 8BIT Message-Id: References: <20170517112107.31025-1-lhenriques@suse.com> To: Luis Henriques X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 18 May 2017 13:36:54 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On 17 May 2017, at 19:21, Luis Henriques wrote: > > Converting a file handle to a dentry can be done call after the inode > unlink. This means that __fh_to_dentry() requires an extra check to > verify the number of links is not 0. > > The issue can be easily reproduced using xfstest generic/426, which does > something like: > > name_to_handle_at(&fh) > echo 3 > /proc/sys/vm/drop_caches > unlink() > open_by_handle_at(&fh) > > The call to open_by_handle_at() should fail, as the file doesn't exist > anymore. > > Cc: stable@vger.kernel.org > Link: http://tracker.ceph.com/issues/19958 > Signed-off-by: Luis Henriques > --- > fs/ceph/export.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/ceph/export.c b/fs/ceph/export.c > index e8f11fa565c5..7df550c13d7f 100644 > --- a/fs/ceph/export.c > +++ b/fs/ceph/export.c > @@ -91,6 +91,10 @@ static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino) > ceph_mdsc_put_request(req); > if (!inode) > return ERR_PTR(-ESTALE); > + if (inode->i_nlink == 0) { > + iput(inode); > + return ERR_PTR(-ESTALE); > + } > } maybe we should do this check in MDS Regards Yan, Zheng > > return d_obtain_alias(inode);