Consider the following C program on x86_64 Linux.

01  #include <stdio.h>
02  #include <stdlib.h>
03  #include <sys/mman.h>
04  #include <unistd.h>
05
06  int main() {
07
08    size_t pagesize = sysconf(_SC_PAGESIZE);
09
10    void *buffer = aligned_alloc(pagesize, pagesize);
11    if (!buffer) {
12        perror("Failed to allocate memory");
13        return EXIT_FAILURE;
14    }
15
16
17    if (mprotect(buffer, pagesize, PROT_READ | PROT_WRITE | PROT_EXEC) == -1) {
18        perror("mprotect - error 1");
19        free(buffer);
20        return EXIT_FAILURE;
21    }
22
23    sprintf((char *)buffer, "This is a test.\n");
24
25    if (mprotect(buffer, pagesize, 0 ) == -1) {
26        perror("mprotect - error2");
27        free(buffer);
28        return EXIT_FAILURE;
29    }
30
31    printf("%s", (char *)buffer);
32    free(buffer);
33
34    return EXIT_SUCCESS;
35  }

Which of the following statement(s) are true?