Comment 10 for bug 1475050

LXC attaches to all namespaces at once. When it attaches to a user namespace, it becomes uid/gid -1/-1 in that namespace, until it setuid/setgid to 0/0.

The question is whether injecting code into the process at that stage (process owned by an unmappable uid/gid but present in the pid and user namespace of the container) should be allowed (probably not) and if allowed, whether the kernel recognizes that process as real root and if so, can that lead to a privilege escalation.