Imun/ffi sandwich #43
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Reported by pwnhacker0x18. Fixed by Peter Cawley. LuaJIT#1152
JIT recording semantics assumes FFI calls are leaf regarding the LuaJIT VM: if the execution exited Lua world through FFI machinery it is not re-entering Lua world again. However, there is a way to break this assumption via FFI: one can re-enter LuaJIT VM via Lua C API used within the particular C routine called via FFI. As a result the following host stack mix is created: | Lua-FFI -> C routine -> Lua-C API -> Lua VM This sort of re-entrancy is not supported by LuaJIT tracing compiler. @mraleph named such kind of the call stack an "FFI sandwich" in the tarantool/tarantool#4427. This changeset introduces the mechanism for Lua-C API callbacks similar to the one implemented for Lua-FFI: trace recording is aborted when the execution re-enters LuaJIT VM. If re-enter is detected while running the particular mcode, the runtime finishes its execution with EXIT_FAILURE code and calls panic routine prior to the exit. Co-authored-by: Vyacheslav Egorov <[email protected]> Co-authored-by: Sergey Ostanevich <[email protected]> Signed-off-by: Igor Munkin <[email protected]>
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