I was trying to install Virtualbox Guest Additions when i received below error. Make sure you have done the steps mentioned here.
/tmp/vbox.0/Makefile.include.header:106: *** Error: KERN_DIR does not point to a directory. Stop. Creating user for the Guest Additions. Creating udev rule for the Guest Additions kernel module.
To resolve above issue,
a) Run below commands to update the latest kernels.
yum -y update kernel yum -y install kernel-devel kernel-headers dkms gcc gcc-c++
b) Reboot VM and execute steps again.