ASLR does not seem to randomize text section

Question

I wanted to make some basic tests on Linux ASLR, so i wrote the following code :

#include <stdio.h>

void funct(){
    int a= 0;
}

void main(){
    int b=0;
    printf("funct : %p\n", &funct);
    printf("var stack : %p\n", &b);
}

When I run this code, the second pointer (which points to a value on the stack) seems randomized as it changes from one execution to another, but not the first pointer.

I tried compiling with -fPIC gcc option, but it doesn't work either.

Also, I already checked that /proc/sys/kernel/randomize_va_space is equal to 2.

Could someone explain what I'm doing wrong ?

Answer 1

The text segment is not typically randomized in ASLR implementations, and this is why Return-Oriented Programming (ROP) chains work. The idea is that the application's own code should be 'safe', so randomizing this memory space would be a waste of resources.

ROP chains are about building a malicious payload using the application's own functionality. A good analogy is that you can take any well meaning sentence, and make it an insult by choosing specific letters or words to make a new meaning.