Well, I think the right thing to do is limit the maximal size to be read
inside the c function (just to make it impossible to pass around large
values). This is basically the same fix just at another place in the code.


http://twistedmatrix.com/trac/ticket/1079 describes the same problem
(but with 64 k read requests: it can even leak with small requests).
The fix there was to really copy those strings around into a StringIO
object.

Note that the code does not read byte by byte when passing in no size
argument. Instead it read recv_size bytes:

            if self._rbufsize <= 1:
                recv_size = self.default_bufsize
            else:
                recv_size = self._rbufsize

This seems clearly wrong to me.