Library loading is performed by:

void * os::dll_load(const char *name, char *ebuf, int ebuflen) 

where the `ebuf` buffer is used for producing error information if the loading fails. However on Windows the `ebuf` value is never checked for null but is used unconditionally e.g.

 // Read system error message into ebuf
  // It may or may not be overwritten below (in the for loop and just above)
  lasterror(ebuf, (size_t) ebuflen);
  ebuf[ebuflen - 1] = '\0';
  Events::log_dll_message(nullptr, "Loading shared library %s failed, error code %lu", name, errcode);
  log_info(os)("shared library load of %s failed, error code %lu", name, errcode);

  if (errcode == ERROR_MOD_NOT_FOUND) {
    strncpy(ebuf, "Can't find dependent libraries", ebuflen - 1);
    ebuf[ebuflen - 1] = '\0';
    JFR_ONLY(load_event.set_error_msg(ebuf);)
    return nullptr;
  }

Whilst it seems a little odd to pass a null buffer and skip error reporting, that is what the JFR code does when loading some of its libraries:

void IphlpDll::initialize(void) {
  _hModule = os::win32::load_Windows_dll("iphlpapi.dll", nullptr, 0);

void PdhDll::initialize(void) {
  _hModule = os::win32::load_Windows_dll("pdh.dll", nullptr, 0);

The Posix code correctly handles a null buffer.

The code for this was added in JDK 6, but it was only in JDK 11 that JFR started passing the null buffers.