CVE request: kernel: 'kill sig -1' must only apply to caller's PID namespace

[Eugene Teo <eugene () redhat com>]

I came across this while reviewing some older upstream patches.

Apparently, it was possible to run kill <sig> -1 to kill processes in
all PID namespaces, and break the isolation of namespaces. The expected
behaviour for this is to only kill processes in its own hierarchy. The
fix uses task_pid_vnr() to check if the process is outside of the
caller's namespace before killing.

PID namespaces was merged in 2.6.24.

References:
http://lwn.net/Articles/259217/
https://bugzilla.redhat.com/show_bug.cgi?id=496031
http://git.kernel.org/linus/d25141a818383b3c3b09f065698c544a7a0ec6e7

Thanks, Eugene
-- 
Eugene Teo / Red Hat Security Response Team