do i need visa for 9 hour layover in Baiyun?

I am flying on an Australian passport from Los Angeles,(I have an American permanent residency status/green Card) to Baiyun airport, have a 9 hour layover, and will not be leaving the airport...I have the exact same flights on my return to U.S, about 5 months later...is there any type of special visa i need, or does my 'direct transit for less then 24 hours' work out OK?? thanks, Jenny