main()
{
    int *a,*b,*c,*d,*e;
    b=malloc(8);
    c=malloc(10); /* Essential so we don't coalesce */
    free(b);
    free(b); /* this should die */
    d=malloc(8); /* we'll get the old b block */
    e=malloc(8); /* the double free flaw means we get the old b block again! */
    if (d==e) { printf("FAIL: Exploitable double free behaviour\n"); }
}