// clang-7 -o example1 example1.c      
// To run using clang with stack protection 
// clang-7 -fsanitize=safe-stack -o example1 example1.c
// To run using gcc 
// gcc example1.c -o example1    

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

void f(char* t){
    int authenticated = 0;
    char buf[4];
    strcpy(buf, t);
    if(authenticated){
        printf("Access allowed!\n");
    } else{
      printf("Access denied!\n");
    }
}

int main(int argc, char* argv[])
{
    f("ABCDEFGHIJKLMNO");
    return 0;
}