Zac Efron's rehab stint was for cocaine addiction?

'High School Musical' star Zac Efron's stint at rehab this year was to overcome cocaine addiction.

The 25-year-old actor, who is otherwise known for his squeaky clean image, entered the rehab earlier this year after his problem spiraled out of control during the filming of Seth Rogen's movie "Neighbors", reported TMZ.

The website quoted several sources claiming that the actor went missing for some days while shooting the film due to his drug problem.

"It was common knowledge he was struggling with cocaine," a source added.