Change Root Password In Rescue Mode

This assumes you've already booted into rescue mode and have the following partition scheme:

/dev/sda1 /boot
/dev/sda2 Linux Swap
/dev/sda3 /

#mkdir /tmp/sda3
#mount /dev/sda3 /tmp/sda3
#chroot /tmp/sda3
#passwd
Changing password for user root.
New UNIX password:
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
#reboot