Using calloc instead of malloc, just for checking arithmetic overflow, is superfluous. You can always write a check or a wrapper for malloc that does that automatically. It is so easy I can write it here:

  _Bool Check( const size_t a , const size_t b )
  {
    if( a > SIZE_MAX / b )
    {
       return false;
    }
    return true;  
  }

(If proper warnings are enabled, it also provides extra integer type checking.)