Install GuestAddition for Fedora 18/19/20

Install guest additions for Fedora

I encountered this problem:

Unable to mount the CD/DVD image /Applications/VirtualBox.app/Contents/MacOS/VBoxGuestAdditions.iso on the machine fedora18. Would you like to force mounting of this medium?

Could not mount the media/drive '/Applications/VirtualBox.app/Contents/MacOS/VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED).

How did I solve this problem?

Host: Mac 10.7.5
VM: Fedora 18


1.
change to the root user using "su"
2. 
yum install kernel* gcc -y
3.
cd /run/media/haifzhan/VBOXADDITIONS_xxx
4.
./VBoxLinuxAdditions.sh

Done!