victim.c below is vulnerable. Denote the exectuable generated from victim.c as victim. If victim is a system program, a user may invoke victim and feed it with a malcious string containing malicious code as the command line argument. The malcious code may eventually run within the context of victim.

$/*$ victim.c $*/$

#include

void f$($char $*$str$)\{$

char foo$[16]$;

strcpy$($foo$,$ str$)$;

$\}$

void main$($int argc, char $**$argv$)\{$

f$($argv$[1])$;

return;

$\}$

Which line of code causes the buffer overflow directly?

line $8$

line $9$

line $4$

line $5$