Disable ASLR in linux executable

noaslr.c

// Disable ASLR in linux executable
//
// This bit of code will disable ASLR when it's linked into a linux executable.
// It's achieved by setting the process personality (ADDR_NO_RANDOMIZE),
// and re-executing itself.
//
// This can be used on programs that are built from source, as well as on
// existing dynamically linked executables through LD_PRELOAD.
//
// Usage (linked statically with program):
// cc -o noaslr.o -c noaslr.c
// cc -o myprog.o -c myprog.c 
// cc -o myprog myprog.o noaslr.o
// ./myprog
//
// Usage (with precompiled binary through LD_PRELOAD):
// cc -shared -o noaslr.so noaslr.c
// LD_PRELOAD="$PWD/noaslr.so" ./myprog

#ifdef __linux__
#include <unistd.h>
#include <sys/personality.h>
__attribute__((constructor))
static void _(int argc, char **argv, char **envp)
{
    int pers = personality(0xffffffff);
    if (!(pers & ADDR_NO_RANDOMIZE) && 
            personality(pers | ADDR_NO_RANDOMIZE) != -1) {
        execve("/proc/self/exe", argv, envp);
    }
}
#endif

z-myprog.c

// Example program to test ASLR
// Prints out the pointers of a few kinds of allocations
// Compare output with and without GCC's -no-pie option, and noaslr.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>

int func(void) {
    return 0;
}

int main() {
    void *mapmem = mmap(NULL, 0x100, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    void *brkmem = sbrk(0x100);
    void *mem = malloc(0x100);
    char sptr[0x100];
    int (*fptr)() = func;
    printf("%p %p %p %p %p\n", mapmem, brkmem, mem, sptr, fptr);
    return fptr();
}