struct _HEAP_USERDATA_HEADER// Size=0x20
{
    struct _SINGLE_LIST_ENTRY SFreeListEntry;// Offset=0x0 Size=0x8
    struct _HEAP_SUBSEGMENT * SubSegment;// Offset=0x0 Size=0x8
    void * Reserved;// Offset=0x8 Size=0x8
    unsigned long long SizeIndex;// Offset=0x10 Size=0x8
    unsigned long long Signature;// Offset=0x18 Size=0x8
};