Karl Pauls created SLING-6640:
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Summary: Race condition in JCR Contentloader deactivate can cause
NullPointerException.
Key: SLING-6640
URL: https://issues.apache.org/jira/browse/SLING-6640
Project: Sling
Issue Type: Bug
Components: JCR
Affects Versions: JCR ContentLoader 2.1.10
Reporter: Karl Pauls
Fix For: JCR ContentLoader 2.2.0
The ContentLoaderService registers itself as a SynchronousBundleListener with
the framework on activate and unregisters in the deactivate method. After it
unregistered it turns around and first calls:
this.bundleContentLoader.dispose();
and then the bundleContentLoader is set to null. The bundleContentLoader is
used in the bundleChanged(BundleEvent) callback of the listener interface.
There seems to be an assumption that there will be no more events received
after the unregistering as a listener - however, that assumption doesn't hold.
The framework gets a snapshot of listeners and calls them so there is a window
where bundleChanged can be invoked after the call to
bundleContentLoader.dispose() or after it is set to null.
Both cases can lead to an NPE (either in the bundleChanged directly because the
bundleContentLoader is null already or inside the bundleContentLoader itself as
it has been disposed) when there is a race between the service being
deactivated and a bundle changing state concurrently.
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