Re: Invalid memory read in io_context::executor_type::post

On Monday, June 29th, 2026 at 8:24 PM, Ruben Perez via Boost <[email protected]> wrote:

> Hi all,
> 
> The continuation version of io_context::executor_type::post [1] seems
> to cause an invalid read when submitting operations that don't inherit
> from continuation_op. try_from_continuation [2] will attempt to read a
> magic number. In continuation_op, the magic is before the continuation
> member [3]. If the submitted operation doesn't inherit from
> continuation_op, this leads to reading potentially unmapped memory.
> 
> Reproducer (build with -fsanitize=address):
> 
> struct my_awaitable {
>    capy::continuation* cont;
> 
>    bool await_ready() const { return false; }
>    std::coroutine_handle<> await_suspend(
>       std::coroutine_handle<> h,
>       capy::io_env const* env) noexcept
>    {
>       cont->h = h;
>       env->executor.post(*cont);
>       return std::noop_coroutine();
>    }
> 
>    int await_resume() const { return 42; }
> };
> 
> capy::task<void> co_main()
> {
>    auto cont = std::make_unique<capy::continuation>();
>    my_awaitable aw{cont.get()};
>    int v = co_await aw;
>    std::cout << "The value is: " << v << std::endl;
> }
> 
> I've also raised an issue in the repo [4].

I'll have a look at the issue now. Fix will likely land in develop-2.
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