[SOLR-13196] NullPointerException in o.a.solr.search.facet.FacetFieldProcessor.findTopSlots()

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: 9.0
• Labels: diffblue newdev

Environment

Steps to reproduce

• Use a Linux machine.
• Build commit ea2c8ba of Solr as described in the section below.
• Build the films collection as described below.
• Start the server using the command ./bin/solr start -f -p 8983 -s /tmp/home
• Request the URL given in the bug description.

Compiling the server

git clone https://github.com/apache/lucene-solr
cd lucene-solr
git checkout ea2c8ba
ant compile
cd solr
ant server

Building the collection

We followed Exercise 2 from the Solr Tutorial. The attached file (home.zip) gives the contents of folder /tmp/home that you will obtain by following the steps below:

mkdir -p /tmp/home
echo '<?xml version="1.0" encoding="UTF-8" ?><solr></solr>' > /tmp/home/solr.xml

In one terminal start a Solr instance in foreground:

./bin/solr start -f -p 8983 -s /tmp/home

In another terminal, create a collection of movies, with no shards and no replication, and initialize it:

bin/solr create -c films
curl -X POST -H 'Content-type:application/json' --data-binary '{"add-field": {"name":"name", "type":"text_general", "multiValued":false, "stored":true}}' http://localhost:8983/solr/films/schema
curl -X POST -H 'Content-type:application/json' --data-binary '{"add-copy-field" : {"source":"*","dest":"_text_"}}' http://localhost:8983/solr/films/schema
./bin/post -c films example/films/films.json

• Assignee: Unassigned
• Reporter: Cesar Rodriguez
• Created: 31/Jan/19 11:28
• Updated: 05/Jul/19 14:10
• Resolved: 05/Jul/19 14:10

Description

Requesting the following URL causes Solr to return an HTTP 500 error response:

http://localhost:8983/solr/films/select?facet.sort=asc&facet=on&bf=2&q=x&facet.version=2&facet.field=genre

The error response seems to be caused by the following uncaught exception:

java.lang.NullPointerException
	at org.apache.solr.search.facet.FacetFieldProcessor.lambda$findTopSlots$1(FacetFieldProcessor.java:325)
	at org.apache.solr.search.facet.FacetFieldProcessor$1.lessThan(FacetFieldProcessor.java:331)
	at org.apache.solr.search.facet.FacetFieldProcessor$1.lessThan(FacetFieldProcessor.java:329)
	at org.apache.lucene.util.PriorityQueue.upHeap(PriorityQueue.java:254)
	at org.apache.lucene.util.PriorityQueue.add(PriorityQueue.java:131)
	at org.apache.solr.search.facet.FacetFieldProcessor.findTopSlots(FacetFieldProcessor.java:363)
	at org.apache.solr.search.facet.FacetFieldProcessorByArray.calcFacets(FacetFieldProcessorByArray.java:114)
	at org.apache.solr.search.facet.FacetFieldProcessorByArray.process(FacetFieldProcessorByArray.java:62)
	at org.apache.solr.search.facet.FacetRequest.process(FacetRequest.java:401)
	at org.apache.solr.search.facet.FacetProcessor.processSubs(FacetProcessor.java:472)
	at org.apache.solr.search.facet.FacetProcessor.fillBucket(FacetProcessor.java:429)
	at org.apache.solr.search.facet.FacetQueryProcessor.process(FacetQuery.java:64)
	at org.apache.solr.search.facet.FacetRequest.process(FacetRequest.java:401)
	at org.apache.solr.search.facet.FacetModule.process(FacetModule.java:139)
	at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:298)
[...]

Removing any parameter in the URL makes the NPE disappear, so all URL parameters seem to be involved.

Method org.apache.solr.search.facet.FacetFieldProcessor.findTopSlots(), at line 316 retrieves the field sortAcc, which is null. This null pointer is subsequently used in a lambda expression, line 325 (and 320!). I guess the problem is that some input validation is missing?

We found this bug using Diffblue Microservices Testing. Find more information on this fuzz testing campaign.

Issue Links

• duplicates: SOLR-13022 JSON Faceting NPE & 500 Error when attempting to sort on non-existent agg (ie: typo)