From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:42477 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752407AbcFEU6N (ORCPT ); Sun, 5 Jun 2016 16:58:13 -0400 Subject: Patch "xfs: disallow rw remount on fs with unknown ro-compat features" has been added to the 4.6-stable tree To: sandeen@redhat.com, billodo@redhat.com, david@fromorbit.com, dchinner@redhat.com, gregkh@linuxfoundation.org Cc: , From: Date: Sun, 05 Jun 2016 13:58:12 -0700 Message-ID: <14651602922679@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled xfs: disallow rw remount on fs with unknown ro-compat features to the 4.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xfs-disallow-rw-remount-on-fs-with-unknown-ro-compat-features.patch and it can be found in the queue-4.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From d0a58e833931234c44e515b5b8bede32bd4e6eed Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Wed, 6 Apr 2016 07:05:41 +1000 Subject: xfs: disallow rw remount on fs with unknown ro-compat features From: Eric Sandeen commit d0a58e833931234c44e515b5b8bede32bd4e6eed upstream. Today, a kernel which refuses to mount a filesystem read-write due to unknown ro-compat features can still transition to read-write via the remount path. The old kernel is most likely none the wiser, because it's unaware of the new feature, and isn't using it. However, writing to the filesystem may well corrupt metadata related to that new feature, and moving to a newer kernel which understand the feature will have problems. Right now the only ro-compat feature we have is the free inode btree, which showed up in v3.16. It would be good to push this back to all the active stable kernels, I think, so that if anyone is using newer mkfs (which enables the finobt feature) with older kernel releases, they'll be protected. Signed-off-by: Eric Sandeen Reviewed-by: Bill O'Donnell Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_super.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1276,6 +1276,16 @@ xfs_fs_remount( return -EINVAL; } + if (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 && + xfs_sb_has_ro_compat_feature(sbp, + XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) { + xfs_warn(mp, +"ro->rw transition prohibited on unknown (0x%x) ro-compat filesystem", + (sbp->sb_features_ro_compat & + XFS_SB_FEAT_RO_COMPAT_UNKNOWN)); + return -EINVAL; + } + mp->m_flags &= ~XFS_MOUNT_RDONLY; /* Patches currently in stable-queue which might be from sandeen@redhat.com are queue-4.6/xfs-disallow-rw-remount-on-fs-with-unknown-ro-compat-features.patch