Checking via Timatic, courtesy of the Emirates visa check indicates that you should not need a visa to transit.
A cross check on Immigration Department of Malaysia web portal notes:
- Transit Visa
This is issued to foreign nationals who require a visa to enter Malaysia on transit to other countries. Foreign nationals on transit without leaving the airport premises and who continue their journey to the next destination with the same flight do not require a transit visa.
The KLIA2 Airport visa information
Transit visa is not required for passengers who meet one of the following conditions:
- Arriving/departing at KLIA
- Have a valid visa issued by one of seven countries
- Flying with Malaysia Airlines or Air Asia
- Staying for less that 120 hours
Also, Sri Lankan nationals are among those eligible to Transit Without Visa (TWOV) and allows a stopover (after clearing Immigration) with:
- Onward ticket for within 120 hours.
- Arrival and departure from the same airport.
- A valid onward ticket and a Single or Multiple Entry Visa issued by and are heading to/from Australia, New Zealand, USA, Japan, China, Taiwan, South Korea
- Passport with a minimum validity of 6 months.
- Printed copy of itinerary and original tickets (PNR/booking number not accepted).
You'll find the above (edited for clarity) on the Kuala Lumpur International Airport visa information.