// 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;
}

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

JnF1b3Q7QUJDREVGJnF1b3Q7Cg==

"ABCDEF"