i m using freertos on stm32f103. i m getting hardfault exception when i debug.
what should i do now

That is very, very little information to provide to expect a useful reply. All I can suggest is that you start by making sure you have read the documentation - starting with the documentation page for the demo you are using (or started with), and then the FAQ: http://www.freertos.org/FAQHelp.html

Regards.