A few issues here. The airlines you choose are point to point airlines so you must clear immigration to check-in again in Korea.
Each airport in Korea is subject to different transit rules.
Timatic says: Korea (Rep.) (KR)
Nationals of any country with a visa issued by Australia,
Austria, Belgium, Canada, Cyprus, Czech Rep., Denmark,
Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland (Rep.), Italy, Latvia, Liechtenstein, Lithuania,
Luxembourg, Malta, Netherlands, New Zealand, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden,
Switzerland, USA or United Kingdom if in transit through
Korea (Rep.) must:
-hold confirmed onward tickets on flights departing within
30 days; when
-arriving from the country that issued the visa (a visa that
expired on departure from that country is accepted) and
departing to a third country.
That would indicate that if you hold a valid USA visa you can transit Korea, even with a point to point ticket.
For Malaysia, assuming you are just transiting an not stopping over for a few days and stay on Air Asia then you will be fine.
Visa required, except for Holders of a valid visa issued by
Australia, China (People's Rep.), Chinese Taipei, Japan, Korea
(Rep.), New Zealand or USA to nationals of Sri Lanka residing
in country of nationality holding confirmed onward tickets for
a max. transit For details, click here time of 120 hours, arriving at
and departing from Kuala Lumpur (KUL) on Malaysia Airlines
(MH) or Air Asia (AK). When transit time is longer than 8 hours it is permitted to leave the transit area if:
Transit between Main Terminal and KLIA2 is
also permitted. When leaving the airport transit area,
passports must be valid for at least 6 months from date of