change the return value to 'cookie' address from the current value $\text{'}1".$

Dump of assembler code for function getbuf:

$0$x$565565$f: push $\%$ebp

$0$x$565565$f: mov $\%$esp,$\%$ebp

$0$x$565565$f: push $\%$ebx

$0$x$565565$f: sub $$0$x$24,\%$esp

$0$x$565565$f: call $0$x$565565$ee x$86.$get$\_$pc$\_$thunk.ax$>$

$0$x$565565$fe : add $$0$x$393$e$,\%$eax

$0$x: sub $$0$xc$,\%$esp

$0$x: lea $-0$x$28(\%$ebp$),\%$edx

$0$x: push $\%$edx

$0$x$5655660$a : mov $\%$eax,$\%$ebx

$0$x$5655660$c : call $0$x$56555$fec

$0$x: add $$0$x$10,\%$esp

$0$x: mov $$0$x$1,\%$eax

$0$x: mov $-0$x$4(\%$ebp$),\%$ebx

$0$x$5655661$c : leave

$0$x$5655661$d : ret

End of assembler dump. and Dump of assembler code for function test:

$0$x$56555$df: push $\%$ebp

$0$x$56555$dfa : mov $\%$esp,$\%$ebp

$0$x$56555$dfc : push $\%$ebx

$0$x$56555$dfd : sub $$0$x$14,\%$esp

$0$x$56555$e: call $0$x$56555$bfx$86.$get$\_$pc$\_$thunk.bx$>$

$0$x$56555$e: add $$0$x$4137,\%$ebx

$0$x$56555$e$0$b : call $0$x$5655634$f

$0$x$56555$e: mov $\%$eax,$-0$x$10(\%$ebp$)$

$0$x$56555$e: call $0$x$565565$f$2$

$0$x$56555$e: mov $\%$eax,$-0$xc$(\%$ebp$)$

$0$x$56555$e$1$b : call $0$x$5655634$f

$0$x$56555$e: mov $\%$eax,$\%$edx

$0$x$56555$e: mov $-0$x$10(\%$ebp$),\%$eax

$0$x$56555$e: cmp $\%$eax,$\%$edx

$0$x$56555$e: je $0$x$56555$e$3$d

$0$x$56555$e: sub $$0$xc$,\%$esp

$0$x$56555$e$2$c : lea $-0$x$259$c$(\%$ebx$),\%$eax

$0$x$56555$e: push $\%$eax

$0$x$56555$e: call $0$x$56555$a$50$

$0$x$56555$e: add $$0$x$10,\%$esp

$0$x$56555$e$3$b : jmp $0$x$56555$e$83$

$0$x$56555$e$3$d : mov $-0$xc$(\%$ebp$),\%$edx

$0$x$56555$e: mov $0$x$1118(\%$ebx$),\%$eax

$0$x$56555$e: cmp $\%$eax,$\%$edx

$0$x$56555$e: jne $0$x$56555$e$6$e

$0$x$56555$e$4$a : sub $$0$x$8,\%$esp

$0$x$56555$e$4$d : pushl $-0$xc$(\%$ebp$)$

$0$x$56555$e: lea $-0$x$2573(\%$ebx$),\%$eax

$0$x$56555$e: push $\%$eax

$0$x$56555$e: call $0$x$56555970$

$0$x$56555$e$5$c : add $$0$x$10,\%$esp

$0$x$56555$e$5$f : sub $$0$xc$,\%$esp

$0$x$56555$e: push $$0$x$3$

$0$x$56555$e: call $0$x$565567$e$7$

$0$x$56555$e: add $$0$x$10,\%$esp

$0$x$56555$e$6$c : jmp $0$x$56555$e$83$

$0$x$56555$e$6$e : sub $$0$x$8,\%$esp

$0$x$56555$e: pushl $-0$xc$(\%$ebp$)$

$0$x$56555$e: lea $-0$x$2556(\%$ebx$),\%$eax

$0$x$56555$e$7$a : push $\%$eax

$0$x$56555$e$7$b : call $0$x$56555970$

$0$x$56555$e: add $$0$x$10,\%$esp

$0$x$56555$e: nop

$0$x$56555$e: mov $-0$x $4(\%$ebp$),\%$ebx

$0$x$56555$e: leave