perl6, 59 bytes

Result

AC

Duration

1230ms

Code [DL]

my$h=get-2;say my$a="*"x my$w=get,"
","*{" "x$w-2}*
"x$h,$a

stdin

18
18

stdout

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

stderr