php, 115 bytes

Result

AC

Duration

948ms

Code [DL]

<?php $h=fgets(STDIN)*1;$w=fgets(STDIN)*1;for($y=$h;$y-->0;)echo"*".str_repeat($y>0&&$y<$h-1?" ":"*",$w-2)."*\n"?>

stdin

52
89

stdout

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

stderr

PHP Notice:  A non well formed numeric value encountered in /volume/CODE on line 1
PHP Notice:  A non well formed numeric value encountered in /volume/CODE on line 1