When doing an exec, selinux updates rlimits in its code of current
process depending on current max. Make sure max or cur doesn't change
in the meantime by grabbing task_lock which do_prlimit needs for
changing limits too.
While at it, use rlimit helper for accessing CPU rlimit a line below.
To have a volatile access too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Oleg Nesterov <oleg@redhat.com>
eb2d55a32b