{task,Executor}::block_on are unsound

rust-embedded-community / async-on-embedded

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{task,Executor}::block_on are unsound #6

Open Nemo157 opened 4 years ago

Nemo157 commented 4 years ago

It is possible for the future passed to block_on to stash a clone of the provided Waker somewhere, then call wake on it after completion, resulting in an attempt to access the ready variable from the freed block_on stack.

Disasm commented 4 years ago

Hmm, is it possible to save this waker in a safe way?

Nemo157 commented 4 years ago

Yes, it could be put into a static WAKER: RefCell<Option<Waker>>; or similar construct.