PVS-Studio warning V512 for samba

static NET_API_STATUS test_netusermodals(
  struct libnetapi_ctx *ctx,
  const char *hostname)
{
  ....
  struct USER_MODALS_INFO_0 *u0 = NULL;
  struct USER_MODALS_INFO_0 *_u0 = NULL;
  ....
  if (memcmp(u0, _u0, sizeof(u0) != 0)) {
    printf("USER_MODALS_INFO_0 struct has changed!!!!\n");
    return -1;
  }
  ....
}

Most likely this is what should be written here: sizeof(*u0).

This suspicious code was found in samba project by PVS-Studio static code analyzer.
Warning message is:
V512 A call of the 'memcmp' function will lead to underflow of the buffer 'u0'. netuser.c 247

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/