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Roman Bogorodskiy
4445d03958
Currently, userdisk_init() iterates through disks and checks whether DIOCGSECTORSIZE and DIOCGMEDIASIZE ioctls are available for the device. If either ioctl fails, userdisk_init() returns ENXIO with ud_info only partially initialized. devinit() records the failure, but loader_main() ignores devinit()'s return value, so later code may access an uninitialized entry. In certain cases this code can still boot from a disk even if userdisk_init() returns ENXIO, for example, when the first of two disks is valid and the second errors out. To address this issue while not breaking the current behavior, do the following: - Zero-initialize the userdisk_info array and use a zero media size to mark disks that do not support the ioctls mentioned above or report an empty medium. - Update userdisk_print() not to print unusable disks. - Update userdisk_open() to return EIO for unusable disks. - Update extract_currdev() to pick the first usable disk instead of the first disk. Introduce userboot_disk_firstunit() for that. Additionally, reset counters on ud_info allocation failure to prevent accessing unallocated data. Reviewed by: jhb (previous version), markj MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D59262