PVS-Studio warning V568 for Apache

PSECURITY_ATTRIBUTES GetNullACL(void)
{
  PSECURITY_ATTRIBUTES sa;

  sa  = (PSECURITY_ATTRIBUTES) LocalAlloc(
    LPTR, sizeof(SECURITY_ATTRIBUTES));
  sa->nLength = sizeof(sizeof(SECURITY_ATTRIBUTES));
  ...
}

This is what should have been written here: sa->nLength = sizeof(SECURITY_ATTRIBUTES);

This suspicious code was found in Apache project by PVS-Studio static code analyzer.
Warning message is:
V568 It's odd that the argument of sizeof() operator is the 'sizeof (SECURITY_ATTRIBUTES)' expression. libhttpd util_win32.c 115

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/