OpenBSD device length detection was returning the raw disk sector count from DIOCGPDINFO directly. That value is not bytes and it describes the physical/default disk label, which caused VeraCrypt to expose an incorrectly sized FUSE backing image through vnd for device-hosted volumes.
Use the current disklabel from DIOCGDINFO, derive the opened partition from the device minor number, and return the selected partition size in bytes. Keep the raw c partition on the whole-disk path by using DL_GETDSIZE there.
Also reject sector-misaligned device-hosted sizes during volume creation so new malformed OpenBSD device-hosted volumes are not created. Do not reject existing malformed headers at mount time, so users can still mount old OpenBSD-created volumes for recovery.
Refs #1589.
Refs #1593.
Mounir IDRASSI
5d7a2a78b8