I find stack overflow security bugs fascinating; and on Linux, compilers still don't protect against stack overflows by default when stack frames are bigger than stack guard pages.
So I went looking around in Android, and thanks to how Android's RPC mechanism allows recursive synchronous callbacks in some cases, I managed to find a way to jump a thread guard page in system_server from shell context and (with very low success rate) get instruction pointer control:
https://project-zero.issues.chromium.org/issues/465827985