[CVE-2012-0055] overlayfs devicefs permissions

[Andy Whitcroft]

CVE-2012-0055
	Using overlayfs with lxc causes tty problems that can kill X.
	Overlayfs needs to honor the necessary cgroup permission calls.

This was only exposed from oneiric and later where we have applied
overlayfs.  Fixes for this have already been applied to precise.
Following this email is a patch for oneiric.  This is a backport of the
proposed upstream fix.

Proposing for oneiric.

-apw