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Thank you for the reply.

Actually no, the Lua script is loaded all the time during runtime. The Lua functions within the script are called using lua_getglobal, here is the exact C++ caller function:

Then stack is being checked using lua_isnil for nil, meaning that function does not exist. It's here the actual crash is happening using Lua 5.4.3 and above. Once I add the called function to my Lua script, the application doesn't crash. With Lua 5.4.2 and older it never crashed, regardless the presence of globals defined in the script.


On 2022-12-03 07:30, bil til wrote:
Am Fr., 2. Dez. 2022 um 19:41 Uhr schrieb Aleksandr Zenkov

Thank you for detail infos , sounds like an interesting and
challenging "coroutine/threading" application.

So my next question is.. What type of security change was made in Lua
5.4.3 to start panicking once a C++ code tried to call a piece of Lua
code that does not exist? I mean, such a security checks never existed
But can you explain in more detail, how a user could try to "call a
piece of Lua that does not exist"?

You mean, run to the end of the main program by some label ::End::, as
e. g. "goto End", and then Lua finished and somehow "runs into

Or you mean, invoking some C function from Lua, and this C function
then would invoke Lua Code which does not exist / possibly mixing up
the Lua stack? (but in this case you usually can be happy if such a
panic message would appear I think...)