[sudo-users] accidentally changed the owner of sudo

[Todd C. Miller]

If you are using a system that does not let you log in as root,
such as Ubuntu or macOS, you will need to boot into single user
mode to repair the permissions and file mode.  On most other
systems you should be able to use "su" to change to the root
account.

To repair the ownership and mode run:

    chown root /usr/bin/sudo
    chmod u+s /usr/bin/sudo

 - todd