java, 188 bytes

Result

AC

Duration

1747ms

Code [DL]

interface A{static void main(String[]a){var s=new java.util.Scanner(System.in);for(int p=s.nextInt(),q=s.nextInt(),i=0;i<p;)System.out.print("*"+(i*p>i+i*i++?" ":"*").repeat(q-2)+"*\n");}}

stdin

28
42

stdout

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

stderr