cpython/Misc/NEWS.d/next/Library/2018-06-26-19-03-56.bpo-33871.XhlrGU.rst

Fixed integer overflow in :func:`os.readv`, :func:`os.writev`,
:func:`os.preadv` and :func:`os.pwritev` and in :func:`os.sendfile` with
*headers* or *trailers* arguments (on BSD-based OSes and macOS).