Building the VirtualBox Guest Additions kernel modules [FAILED]
Your system does not seem to be set up to build kernel modules.
Look at /var/log/vboxadd-install.log to find out what went wrong.
Once you have corrected it, you can run /etc/init.d/vboxadd setup to build them.
#gedit /var/log/vboxadd-install.log 内容
Makefile:23: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=<directory> and run Make again.. Stop.
Creating user for the Guest Additions.
Creating udev rule for the Guest Additions kernel module.
#yum install gcc
# yum install gcc kernel-devel kernel-headers