Why does this memory address %fs:0x28 ( fs[0x28] ) have a random value?

Question

I\'ve written a piece of C code and I\'ve disassembled it as well as read the registers to understand how the program works in assembly.

int test(char *this)         


        

Answer 1

glibc:
  uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
# ifdef THREAD_SET_STACK_GUARD
  THREAD_SET_STACK_GUARD (stack_chk_guard); 

the _dl_random from kernel.