python3, 81 bytes

Result

WA

Duration

872ms

Code [DL]

h=int(input())
w=int(input())
s='*'*w+'\n'
print(s+('\n*'+' '*(w-2)+'*')*(h-2)+s)

stdin

28
28

stdout

****************************

*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *
*                          *****************************

stderr

strace