Oh I see, you're worried that the TV manufacturer could hack your laptop if you connect it via HDMI. This is the point at which I have to wonder: what on earth can HDMI do?? What is the vector? I assume you have to break out of the target driver, which is probably OS/version specific. Then I suppose normal hackery applies, in terms of planting something on the disk. I assume that the HDMI driver does NOT have any legit API for writing to arbitrary locations on disk. I assume.
I know nothing about the HDMI spec, but according to other comments, Ethernet over HDMI is a thing. So in theory perhaps the TV could present itself as a network device and then MITM your traffic. Not sure if that's actually possible though.
