pwn2.c

// Linux 32bit: gcc -pwn2.c
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>

#define maxlen 20

struct {
	int admin;
	int buffer[maxlen];
} array;

void print_arr(int buf[]) {
	int i;
	printf ("buffer: ");
	for (i=0; i<maxlen; ++i)
		printf ("%d ", buf[i]);
	printf ("\n");
}

int main () {
	srand(time(0));
	int i;
	array.admin = 0;
	for (i=0; i<maxlen; ++i)
		array.buffer[i] = rand() % 10;
	print_arr(array.buffer);
	puts("Input the element you want to change value: ");
	int ind; 
	scanf("%d", &ind);
	if ( ind < maxlen ) {
		puts("New value: ");
		int val;
		scanf("%d", &val);
		array.buffer[ind] = val;
	}
	else {
		puts("Failed!");
	}
	if ( array.admin == 1 ) {
		puts("You win!");
	}
	return 0;
}