Re: [PATCH v4.4.y] ext4: never move the system.data xattr out of the inode body

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Sep 28, 2018 at 09:21:44AM -0700, Zubin Mithra wrote:
> From: Theodore Ts'o <tytso@mit.edu>
> 
> commit 8cdb5240ec5928b20490a2bb34cb87e9a5f40226 upstream.
> 
> When expanding the extra isize space, we must never move the
> system.data xattr out of the inode body.  For performance reasons, it
> doesn't make any sense, and the inline data implementation assumes
> that system.data xattr is never in the external xattr block.
> 
> This addresses CVE-2018-10880
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=200005
> 
> Backport Note:
> - dfa2064b22("ext4: factor out loop for freeing inode xattr space")
> factored out the loop from inside ext4_expand_extra_isize_ea to a
> separate function named ext4_xattr_make_inode_space. As the above commit
> is not present in 4.4.y, make the change inside ext4_expand_extra_isize_ea.


What about a 4.9.y version of this?  I can't just take a 4.4 version
because someone would suffer a regression if they moved from 4.4.y to
4.9.y :(

thanks,

greg k-h