Fix use-after-free in TCrossConnectionBase.Close

[Vizit0r]

procedure TCrossConnectionBase.Close;
begin
  if (_SetConnectStatus(csClosed) = csClosed) then Exit;

  if (FSocket <> INVALID_SOCKET) then
  begin
    FOwner.TriggerDisconnected(Self);   // <-- may destroy Self
    InternalClose;                      // <-- on freed memory
    FSocket := INVALID_SOCKET;          // <-- on freed memory
  end;
end;

Self is an object reference being passed where an ICrossConnection is expected, so the compiler materialises a temporary interface reference and releases it at the end of that statement. Inside the call, TriggerDisconnected does

FConnections.Remove(AConnection.UID);
...
LogicDisconnected(AConnection);

Either the list removal or the user callback can drop the last remaining reference to the connection. When that happens, the temporary is the only thing keeping the object alive, and it is gone by the time InternalClose and the FSocket reset run — both then touch freed memory.

Most call sites happen to be safe because they hold their own LConnection: ICrossConnection local, so this only bites on the paths where the caller's reference has already been dropped.

Fix

Hold an ICrossConnection for the whole method. Two lines, no behaviour change on the paths that were already safe.

How it showed up

EUseAfterFreeError in production (FastMM full-debug), reached through TIocpCrossSocket.Send -> AConnection.Close on an already-dead socket.

Checked

Compiles clean on Win64 (Delphi 37.0) — no new warnings or hints.