The WirePlumber module registers three async callbacks (onDefaultNodesApiLoaded,
onMixerApiLoaded, onPluginActivated) that receive a raw self pointer with a NULL
GCancellable. WirePlumber cannot withdraw an in-flight callback, so if the module
is destroyed before a queued callback fires (e.g. a temporary output/bar is removed
while a component load is still pending, or during an audio route transition), the
callback dereferences the freed self, causing heap corruption / a crash.
Guard each of these callbacks with isModuleAlive(), which checks the existing static
modules registry. The destructor already removes this from the registry before any
teardown, so a missing entry means self is dangling and the callback bails out
without touching it.
A GCancellable cannot fix this cleanly here: every callback dereferences self on its
first line, and wp_core_load_component completes via a WpTransition (not a GTask), so
the cancellable is not recoverable from the GAsyncResult either. The liveness check
must not touch self at all.
Fixes#3974.
Alex
8664d9a963