[SOLR-13194] NullPointerException in org/apache/solr/handler/component/ExpandComponent.java[240]

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Won't Fix
• 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: Marek
• Created: 31/Jan/19 11:12
• Updated: 12/Dec/19 05:06
• Resolved: 12/Dec/19 05:06

Description

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

http://localhost:8983/solr/films/select?expand=true&fq={!collapse%20field=id}&group=true&group.func=genre

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

ERROR (qtp689401025-38) [   x:films] o.a.s.s.HttpSolrCall null:java.lang.NullPointerException
	at org.apache.solr.handler.component.ExpandComponent.process(ExpandComponent.java:240)
	at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:298)
	at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:199)
	at org.apache.solr.core.SolrCore.execute(SolrCore.java:2559)
	at org.apache.solr.servlet.HttpSolrCall.execute(HttpSolrCall.java:711)
	at org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:516)
	at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:394)
	at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:340)

There is called method 'size' on the variable 'docList', which is null. The null value comes from parameter 'rb' (an instance of class 'org.apache.solr.handler.component.ResponseBuilder'), where 'rb.results.docList' is assigned to the mentioned local variable 'docList'.

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

Issue Links

• is related to: SOLR-13970 Collapse/Expand and Grouping are not designed to work together, we should fail requests that specify both gracefully