Merge tag 'hardening-v6.14-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening fixes from Kees Cook:
 "This is a fix for the soon to be released GCC 15 which has regressed
  its initialization of unions when performing explicit initialization
  (i.e. a general problem, not specifically a hardening problem; we're
  just carrying the fix).

  Details in the final patch, Acked by Masahiro, with updated selftests
  to validate the fix"

* tag 'hardening-v6.14-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  kbuild: Use -fzero-init-padding-bits=all
  stackinit: Add union initialization to selftests
  stackinit: Add old-style zero-init syntax to struct tests