kobject_uevent_env() uses envp_ext[] as verbatim format string which
can cause problems ranging from unexpectedly mangled string to oops if
a string in envp_ext[] contains substring which can be interpreted as
format.  Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>