[Precise CVE-2013-0871] race conditon in ptrace

[Luis Henriques]

>From the description:

 "A race conditon in ptrace can lead to kernel stack corruption and
  arbitrary kernel-mode code execution."

I was able to reproduce this issue running Precise on KVM, with 4 CPUs.

Following this email, there are 3 patches that should fix this issue for
Precise.  These patches have been prepared by Brad and I couldn't reproduce
the bug using these patches.