Endless Loop in org.apache.sling.models.impl.AdapterImplementations (latest Code)

[Andreas Schaefer <sc...@me.com>]

Hi

In AEM 6.4.0 load 20 they use a version of org.apache.sling.models.impl (1.4.7…).

Using a Content Fragment the loopup for a Model fails and then we end up in an endless loop
because the org.apache.sling.models.impl.AdapterImplementations.getModelClassForResource()
is looked up with a resource that points to /index.servlet. The resource type of that is /index.servlet
leading to an endless loop.

Looking at the code there should be a way to exit in erroneous conditions like this one. The is
also the chance that a parent resource type points back to a child (not sure if that is possible)
which would also cause an endless loop.

For starters a check if the resource type resource is not posting to the same resource as the
given resource before calling the method again would at least guard against issues were the
resource type is the same as the resource.

Most likely there is something going wrong beforehand but a StackOverflowError is not a good thing.

Here is the stack trace:

java.lang.StackOverflowError
	at org.apache.jackrabbit.oak.segment.MapRecord.getEntry(MapRecord.java:161)
	at org.apache.jackrabbit.oak.segment.MapRecord.getEntry(MapRecord.java:173)
	at org.apache.jackrabbit.oak.segment.SegmentNodeState.getChildNode(SegmentNodeState.java:423)
	at org.apache.jackrabbit.oak.plugins.memory.MemoryNodeBuilder.<init>(MemoryNodeBuilder.java:143)
	at org.apache.jackrabbit.oak.segment.SegmentNodeBuilder.<init>(SegmentNodeBuilder.java:93)
	at org.apache.jackrabbit.oak.segment.SegmentNodeBuilder.createChildBuilder(SegmentNodeBuilder.java:148)
	at org.apache.jackrabbit.oak.plugins.memory.MemoryNodeBuilder.getChildNode(MemoryNodeBuilder.java:331)
	at org.apache.jackrabbit.oak.core.SecureNodeBuilder.<init>(SecureNodeBuilder.java:112)
	at org.apache.jackrabbit.oak.core.SecureNodeBuilder.getChildNode(SecureNodeBuilder.java:329)
	at org.apache.jackrabbit.oak.core.MutableTree.getTree(MutableTree.java:290)
	at org.apache.jackrabbit.oak.core.MutableRoot.getTree(MutableRoot.java:220)
	at org.apache.jackrabbit.oak.core.MutableRoot.getTree(MutableRoot.java:69)
	at org.apache.jackrabbit.oak.jcr.delegate.SessionDelegate.getItem(SessionDelegate.java:442)
	at org.apache.jackrabbit.oak.jcr.session.SessionImpl.getItemInternal(SessionImpl.java:167)
	at org.apache.jackrabbit.oak.jcr.session.SessionImpl.access$400(SessionImpl.java:82)
	at org.apache.jackrabbit.oak.jcr.session.SessionImpl$3.performNullable(SessionImpl.java:229)
	at org.apache.jackrabbit.oak.jcr.session.SessionImpl$3.performNullable(SessionImpl.java:226)
	at org.apache.jackrabbit.oak.jcr.delegate.SessionDelegate.performNullable(SessionDelegate.java:243)
	at org.apache.jackrabbit.oak.jcr.session.SessionImpl.getItemOrNull(SessionImpl.java:226)
	at com.adobe.granite.repository.impl.CRX3SessionImpl.getItemOrNull(CRX3SessionImpl.java:98)
	at org.apache.sling.jcr.resource.internal.helper.jcr.JcrItemResourceFactory.getItemOrNull(JcrItemResourceFactory.java:184)
	at org.apache.sling.jcr.resource.internal.helper.jcr.JcrItemResourceFactory.createResource(JcrItemResourceFactory.java:96)
	at org.apache.sling.jcr.resource.internal.helper.jcr.JcrResourceProvider.getResource(JcrResourceProvider.java:320)
	at org.apache.sling.resourceresolver.impl.providers.stateful.AuthenticatedResourceProvider.getResource(AuthenticatedResourceProvider.java:135)
	at org.apache.sling.resourceresolver.impl.helper.ResourceResolverControl.getResource(ResourceResolverControl.java:227)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getAbsoluteResourceInternal(ResourceResolverImpl.java:1048)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getResourceInternal(ResourceResolverImpl.java:674)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getResource(ResourceResolverImpl.java:628)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getResourceInternal(ResourceResolverImpl.java:685)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getResource(ResourceResolverImpl.java:628)
	at org.apache.sling.resourceresolver.impl.helper.ResourceResolverControl.getParentResourceType(ResourceResolverControl.java:733)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getParentResourceType(ResourceResolverImpl.java:1219)
	at org.apache.sling.models.impl.AdapterImplementations.getModelClassForResource(AdapterImplementations.java:318)
	at org.apache.sling.models.impl.AdapterImplementations.getModelClassForResource(AdapterImplementations.java:322)
	at org.apache.sling.models.impl.AdapterImplementations.getModelClassForResource(AdapterImplementations.java:322)

Re: Endless Loop in org.apache.sling.models.impl.AdapterImplementations (latest Code)

[Bertrand Delacretaz <bd...@apache.org>]

Hi,

On Thu, Feb 15, 2018 at 3:51 AM, Andreas Schaefer <sc...@me.com> wrote:
> ...org.apache.sling.models.impl.AdapterImplementations.getModelClassForResource()
> is looked up with a resource that points to /index.servlet. The resource type of that is /index.servlet
> leading to an endless loop....

Could you provide a test case that reproduces the issue? Disabled with
@Ignore for now, I guess ;-)

-Bertrand