NtSetDefaultLocale and ExpSetCurrentUserUILanguage do not probe the given locale or language ID,
and as a result of that these functions would happily take any given argument. This is problematic
because overwriting NLS data (specifically the Default registry key value as its gets set by the
NtSetDefaultLocale syscall itself) with garbage stuff, rendering the system completely unbootable.
In addition to that, these functions do not check the captured language/locale ID against pre-determined
locales or languages pre-installed in the system. This basically means an ID of 1, for example, is still
valid because it is not bogus albeit there is no such a locale of an ID of 1. That value would get passed
to the Default value key and that renders the system unbootable as well.
CORE-18100
6438b85605