bash-busybox, 138 bytes

Result

AC

Duration

1248ms

Code [DL]

read h
read w
a=$(printf %${w}s|sed 's/ /*/g')
((h-=2))
((w-=2))
b=\*$(printf %${w}s)\*
echo "$a"
printf %${h}s|sed "s/ /$b\n/g"
echo "$a"

stdin

32
45

stdout

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

stderr