fix(asr): prevent use-after-free in MLX callback on cancel#27
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When Rust calls close() on the MLX provider, it invokes koe_mlx_cancel() then immediately frees the leaked Sender pointer. But Swift's Task.cancel() is cooperative — the eventTask may still invoke the C callback with the freed context pointer. Add an NSLock to MLXAsrManager so that cancel() clears callback/ctx under the lock before cancelling the task, and invokeCallback() holds the lock for the entire C callback invocation. This guarantees the pointer is never dereferenced after Rust reclaims it.
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Problem
When Rust calls
close()on the MLX provider, it invokeskoe_mlx_cancel()then immediately frees the leakedBox<Sender>viareclaim_sender(). However, Swift'sTask.cancel()is cooperative — theeventTaskmay still be running and can invoke the C callback with the already-freed context pointer, leading to a use-after-free crash.Solution
Add an
NSLocktoMLXAsrManager:cancel()clearscallback/callbackCtxunder the lock before cancelling the taskinvokeCallback()holds the lock for the entire C callback invocationThis guarantees the context pointer is never dereferenced after Rust reclaims it. A safety-invariant comment is added to the Rust side.
Files changed
Packages/KoeMLX/Sources/KoeMLX/MLXAsrManager.swiftkoe-asr/src/mlx.rs(comment only)Test plan
make buildpasses