The hpt{nr,rr} ioctl handler allocates a buffer without M_ZERO and calls
hpt_do_ioctl(), which might not overwrite the entire buffer.
Also zero bytesReturned in case it is not written by hpt_do_ioctl().
The hpt27{nr,rr} device has permissions only for root so this is not urgent,
and the fix can be MFCd and considered for a future EN.
The same issue was reported in the hpt27xx driver by Ilja Van Sprundel.
Reviewed by: jhb, kib
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
5d8501f487