From: Eric Sandeen <sandeen@sandeen.net>
To: Dave Chinner <david@fromorbit.com>, Eric Sandeen <sandeen@redhat.com>
Cc: Jan Kara <jack@suse.cz>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs: take XFS_IOLOCK_EXCL if suid removal is required
Date: Mon, 15 Jun 2015 10:26:37 -0500 [thread overview]
Message-ID: <557EEEAD.8000701@sandeen.net> (raw)
In-Reply-To: <20150306210927.GA13958@dastard>
On 3/6/15 3:09 PM, Dave Chinner wrote:
> On Fri, Mar 06, 2015 at 10:54:06AM -0600, Eric Sandeen wrote:
>> This sequence:
>>
>> # rm -f sparsefile
>> # truncate --size=1m sparsefile
>> # chmod ugo+rws sparsefile
>> # ls -l sparsefile
>> -rwSrwSrw-. 1 root root 1048576 Mar 6 10:29 sparsefile
>> # su tester
>>
>> $ xfs_io -d -c "pwrite 0 4096" sparsefile
>> wrote 4096/4096 bytes at offset 0
>> 4 KiB, 1 ops; 0.0000 sec (21.505 KiB/sec and 5.3763 ops/sec)
>> $ exit
>>
>> will lead to a WARN_ON() in notify change, because i_mutex is
>> not held, and we get to notify_change via suid removal with
>> only XFS_IOLOCK_SHARED held, i.e. no i_mutex.
>>
>> Upgrade the lock to XFS_IOLOCK_EXCL in this case.
>>
>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>
> I believe Jan Kara has already addressed this problem in
> this patchset:
>
> http://oss.sgi.com/archives/xfs/2015-03/msg00051.html
Seems like that patchset never made it anywhere, though, so this
is still an outstanding problem. :(
-Eric
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next prev parent reply other threads:[~2015-06-15 15:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-06 16:54 [PATCH] xfs: take XFS_IOLOCK_EXCL if suid removal is required Eric Sandeen
2015-03-06 21:09 ` Dave Chinner
2015-03-09 14:28 ` Eric Sandeen
2015-06-15 15:26 ` Eric Sandeen [this message]
2015-07-09 10:17 ` Jan Kara
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