O'Halloran has returned to Villa after sustaining a cruciate ligament injury and said: "Unfortunately, it's a bad one. It's my cruciate ligaments.
"I haven't got the full details as yet, so we'll wait and see what happens over the next few weeks. Unfortunately, it means it's loan over for me.
"I was looking forward to playing here, but I'm not going to be all negative about things, you never know what might happen in the future."