Comment 4 for bug 559545

The /dev/shm items in /etc/apparmor.d are AppArmor profile abstractions-- for AppArmor profiles that use these abstractions, they only grant access to the files you see. They do not change permissions of the files in any way. An application may do this. My ppa is https://launchpad.net/~jdstrand/+archive/ppa/+packages and it contained libvirt 0.7.7 packages.

I asked the question because some people like to put virtual machines in /dev/shm and libvirt 0.7.7 will change permissions of files., and libvirt uses AppArmor. If you only ever installed libvirt from Ubuntu (latest is 0.7.5), then libvirt is not to blame. Can you check to see what version of libvirt you had installed?