From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 4775529DFB for ; Sun, 13 Oct 2013 16:52:27 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 54E33304032 for ; Sun, 13 Oct 2013 14:52:13 -0700 (PDT) Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id A0FrL1VDxeyvSzbC for ; Sun, 13 Oct 2013 14:52:11 -0700 (PDT) Date: Mon, 14 Oct 2013 08:52:08 +1100 From: Dave Chinner Subject: Re: [PATCH 2/4] xfs: reject completely bogus remount options Message-ID: <20131013215208.GE5663@dastard> References: <52584C8A.1060808@redhat.com> <52584D56.7090902@sandeen.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <52584D56.7090902@sandeen.net> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: Eric Sandeen , xfs-oss On Fri, Oct 11, 2013 at 02:11:18PM -0500, Eric Sandeen wrote: > There's a long comment about handling non-remountable > options in xfs_fs_remount, but nothing addresses the case > of completely bogus mount options at remount time, which > can lead to some severe strangeness: > > # for I in `seq 1 10`; do mount -o remount,noacl /mnt/test2; done > # for I in `seq 1 10`; do mount -o remount,badoption /mnt/test2; done > # grep sdb4 /etc/mtab > /dev/sdb4 /mnt/test2 xfs rw,noacl,noacl,noacl,noacl,noacl,noacl,noacl,noacl,noacl,noacl,noacl,badoption,badoption,badoption,badoption,badoption,badoption,badoption,badoption,badoption,badoption 0 0 > > This is a bit of a hack, but we can re-use xfs_parseargs() > with a dummy mount struct to just vet all of the remount > options which were passed in. With this, we get a saner > result: > > [44898.102990] EXT4-fs (sdb4): Unrecognized mount option "badoption" or missing value ext4? Really? :) > +++ b/fs/xfs/xfs_super.c > @@ -1202,11 +1202,25 @@ xfs_fs_remount( > int *flags, > char *options) > { > - struct xfs_mount *mp = XFS_M(sb); > + struct xfs_mount *mp = XFS_M(sb), *dummy_mp; > substring_t args[MAX_OPT_ARGS]; > char *p; > int error; > > + /* > + * Check all the mount options presented to be sure > + * there's nothing too crazy in there. Non-remountable > + * but valid options are a different issue. > + */ > + dummy_mp = kmem_zalloc(sizeof(*dummy_mp), KM_MAYFAIL); > + if (dummy_mp) { > + dummy_mp->m_super = sb; > + error = xfs_parseargs(dummy_mp, options); > + kfree(dummy_mp); > + if (error) > + return -error; This, at minimum, leaks dummy_mp->m_fsname, and it will leak other strings that are also kstrdup()d by xfs_parseargs(). Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs