This question was asked and answered over at superuser.com:

You need to turn off the journaling if you want to write to it from
Ubuntu. Ubuntu only has support for writing to non-journaled HFS+
volumes.

On your Mac:

• Open Disk Utility under Applications -> Utilities


• Select the volume to disable journaling on.


• Choose Disable Journaling from the File menu. (On later Mac OS versions you'll have to hold down the option button when you click
  the File menu. Or if you like Apple+J)

Journaling is a feature that helps prevent file-system corruption in case of sudden loss of power or major crash and also helps speed recovery during a filesystem check. Just so you know what you will be disabling. You can use a file-system without journaling, you just might have to wait longer and deal with more problems if your computer crashes or loses power.

Support for read+write access with journalling for HFS+ partitions is still in progress. You can forcibly enable it with recent kernels, but it's still considered unsafe [source].