Question

Why doesn’t this code print “test”?

#include <stdio.h>
#include <stdlib.h>

void foo ( void ) {
   printf("test\n");
}

__declspec(naked)
void bar ( void ) {
   asm {
      push 0x000FFFFF
      call malloc
      pop ecx
      push eax
      add eax, 0x000EFFFF

      mov ecx, esp
      mov esp, eax
      push ecx

      call foo

      pop esp
      call free
      pop ecx
      ret
   }
}

int main(int argc, char* argv[])
{
   bar();
   return 0;
}

Answer 1

Because your newly allocated stack is not DWORD aligned. Change code to this:

  push 0x00100000
  call malloc
  pop ecx
  push eax
  add eax, 0x000f0000

… and it will print as needed.

Be sure to add \n to avoid buffering issues as advised by Paul.