#include <stdio.h> #include <stdlib.h> #include <string.h> int main() { char *x = malloc(sizeof("Hello World!")); strcpy(x, "Hello World!"); printf("%s\n", x); free(x); *(volatile char *) (x - 4096); } // 11 // stdout: Hello World! // stderr: Invalid heap access: address 0x100000ff3 is not in an allocation or was already freed // stderr: at bin/hello_header_after_free(main+0x4f) // stderr: main // stderr: hello_header_after_free.c:10