Create buffer overflows in snow leopard

As part of a course at university in computer security, I'm soon about to learn about buffer overflows and how to use them to as exploits. I'm trying to do some simple buffer overflow with the following code:

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[])
{
    char buffer_one[4], buffer_two[16];

    strcpy(buffer_one, "one");
    strcpy(buffer_two, "two");

    strcpy(buffer_one, argv[1]);

    printf("buffer_two is at %p and contains \'%s\'\n", buffer_two, buffer_two);
    printf("buffer_one is at %p and contains \'%s\'\n", buffer_one, buffer_one);
}

I'm able to overwrite the content of buffer_one with the null terminator if i run

$./overflow 1234567890123456
 buffer_two is at 0x7fff5fbff8d0 and contains '1234567890123456'
 buffer_one is at 0x7fff5fbff8e0 and contains ''

But if i send more than 16 characters as argument, the program sends Abort trap. I supposed this is some sort of buffer protection on Snow Leopard (ASLR maybe?). If if make the size of buffer_two < 16, the adresse is still 16 bits apart

I'm running gcc -o overflow overflow.c -fno-stack-protector to remove stack protection

Is there any solution to this problem, other than installing a VM running a linux dist.?