Argh @ Linux 2.6.12
En hierom was dynamite dus stuk:
[PATCH] Randomisation: mmap randomisation The patch below randomizes the starting point of the mmap area. This has the effect that all non-prelinked shared libaries and all bigger malloc()s will be randomized between various invocations of the binary. Prelinked binaries get a address-hint from ld.so in their mmap and are thus exempt from this randomisation, in order to not break the prelink advantage. The randomisation range is 1 megabyte (this is bigger than the stack randomisation since the stack randomisation only needs 16 bytes alignment while the mmap needs page alignment, a 64kb range would not have given enough entropy to be effective)
En zo fix je dat dus:
#include <stdio.h>
#include <linux/personality.h>
#include <sys/syscall.h>
#include <unistd.h>
#ifndef ADDR_NO_RANDOMIZE
#define ADDR_NO_RANDOMIZE (0x0040000)
#endif
int main(int argc, char* argv[]) {
char buf[21];
int sc_ret;
FILE* fd;
#ifdef FIXMAPS
sc_ret = syscall(SYS_personality,ADDR_NO_RANDOMIZE);
if(!sc_ret) { /* Syscall succeeded, execute ourselves again */
execvp(argv[0],argv);
}
else if(!(sc_ret & ADDR_NO_RANDOMIZE)) { /* Setting personality failed */
perror("Setting personality failed");
exit(1);
}
#endif
fd = fopen("/proc/self/maps", "r");
buf[20] = '';
while(!feof(fd)) {
fread(buf, 1, 20, fd);
fputs(buf,stdout);
}
}
Compileer met gcc -o main main.c en run het meerder malen. De mappings veranderen steeds. Compileer daarna met gcc -o main main.c -DFIXMAPS en je ziet: de mappings blijven hetzelfde. De stack mapping is wel nog steeds stuk, maar die wordt toch op een andere manier teruggezet. Ik heb goede hoop dat dit alle problemen oplost
. Maar gelukkig heeft Merel die achter me aan gebracht, dus was ik slechts een half uur later dan gepland (wat nog steeds op tijd was) op de Kruislaan