Re: xfs: commit 6552321831dc "xfs: remove i_iolock and use i_rwsem in the VFS inode instead" change causes hang

From	Mimi Zohar <zohar@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Re: xfs: commit 6552321831dc "xfs: remove i_iolock and use i_rwsem in the VFS inode instead" change causes hang
Date	2017-01-08 21:20 +0100
Message-ID	<sXs6B-2Mo-3@gated-at.bofh.it> (permalink)
References	(2 earlier) <sXpV8-16G-33@gated-at.bofh.it> <sXqeu-1ue-9@gated-at.bofh.it> <sXqRb-1KB-21@gated-at.bofh.it> <sXrax-28V-9@gated-at.bofh.it> <sXrkd-2cp-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Sun, 2017-01-08 at 19:26 +0000, Al Viro wrote:
> On Sun, Jan 08, 2017 at 08:09:55PM +0100, Christoph Hellwig wrote:
> 
> > No.  We need an ->ima_measure file_operation, guts of process_measurement
> > turned into a library function that the FS can call after taking fs-specific
> > locks.  And maybe also a small wrapper around it that takes ilock and
> > can be used directly for file systems not needing special locking.
> 
> Incidentally, it had been literally years since the problems with their
> pathname handling had been brought up and we *still* have got no answer.

> In the current tree, ima_d_path() is quite capable of returning
> path->dentry->d_name.name.  Which gets used by subsequent code,
> even though there is no warranty whatsoever that it won't be
> pointing to freed memory by the time the caller of ima_d_path()
> gets it.

The pathname/filename is being used in the measurement list and for
audit logging.  It's currently using d_absolute_path() to get the full
pathname, but falls back to using the dentry->d_name.name on failure.
Ok, so instead of returning the dentry->d_name.name, we should make a
copy it, assuming the error isn't memory related.

Mimi

Thread

xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem in  the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-08 15:50 +0100
  Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use         i_rwsem in the VFS inode instead"  change causes hang Christoph Hellwig <hch@lst.de> - 2017-01-08 16:00 +0100
    Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use    i_rwsem  in the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-08 16:10 +0100
      Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use         i_rwsem in the VFS inode instead"  change causes hang Christoph Hellwig <hch@lst.de> - 2017-01-08 16:20 +0100
        Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use         i_rwsem in the VFS inode instead"  change causes hang Christoph Hellwig <hch@lst.de> - 2017-01-08 16:40 +0100
          Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use    i_rwsem  in the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-08 17:40 +0100
            Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use         i_rwsem in the VFS inode instead"  change causes hang Christoph Hellwig <hch@lst.de> - 2017-01-08 17:50 +0100
        Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use    i_rwsem  in the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-08 16:40 +0100
    Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-08 19:00 +0100
      Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use         i_rwsem in the VFS inode instead"  change causes hang Christoph Hellwig <hch@lst.de> - 2017-01-08 19:20 +0100
        Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-08 20:00 +0100
          Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use         i_rwsem in the VFS inode instead"  change causes hang Christoph Hellwig <hch@lst.de> - 2017-01-08 20:20 +0100
            Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang Al Viro <viro@ZenIV.linux.org.uk> - 2017-01-08 20:30 +0100
              Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-08 21:20 +0100
            Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use    i_rwsem  in the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-08 20:50 +0100
            Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang Jeff Layton <jlayton@redhat.com> - 2017-01-09 20:50 +0100
              Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-10 04:00 +0100
                Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang Jeff Layton <jlayton@redhat.com> - 2017-01-10 17:30 +0100
          Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use i_rwsem  in the VFS inode instead"  change causes hang Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-01-08 20:20 +0100

csiph-web