gistfile1.h

#include <stdio.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <string.h>
#define PAGESIZE 4096
typedef unsigned char byte;

int main (int argc, char const *argv[])
{
	byte* a = (byte*)malloc(PAGESIZE);
	memset(a, 0xcd, PAGESIZE);
	byte* b = (byte*)valloc(PAGESIZE);
	memset(b, 0xab, PAGESIZE);
	mprotect(b, PAGESIZE, PROT_NONE);
	free(a);
	free(b);
	return 0;
}