[Tarantool-patches] [PATCH luajit] core: fix cur_L restoration on error throw

Kirill Yukhin kyukhin at tarantool.org
Thu Aug 19 10:42:43 MSK 2021


On 16 авг 13:19, Sergey Kaplun wrote:
> This change is a kind of revertion of commits
> ed412cd9f55fe87fd32a69c86e1732690fc5c1b0 ('Update cur_L on exceptional
> path') and 97699d9ee2467389b6aea21a098e38aff3469b5f ('Fix cur_L tracking
> on exceptional path').
> When an error is thrown on the coroutine that is not the one being
> currently executed, `cur_L` is not set up. Hence, when the running trace
> exits at assertion guard right after the error is caught, Lua state is
> restored from the incorrect `cur_L`. As a result the resulting stack is
> inconsistent and the crash occurs.
> Aforementioned patches fix the behaviour only for x86/x64
> architectures. This patch updates the `cur_L` within `lj_err_throw()` to
> the given lua_State, where the error is raised, since this is the only
> coroutine that can proceed later. Also, it removes unnecessary
> restorations of `cur_L` at C and FF exception handlers in the VM.
> Nevertheless, throwing an error at non-currently executed coroutine is a
> violation of Lua/C API. So, in the nearest possible future this patch
> should be replaced within the corresponding assert.
> Resolves tarantool/tarantool#6189
> Relates to tarantool/tarantool#6323
> Follows up tarantool/tarantool#1516


Regards, Kirill Yukhin

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