8:59 a.m.
Masafumi Miura created JBEE-184:
-----------------------------------
Summary: NullPointerException happens at ELEvaluator.parseExpressionString()
due to a concurrency issue
Key: JBEE-184
URL: https://issues.jboss.org/browse/JBEE-184
Project: JBoss JavaEE Spec APIs
Issue Type: Bug
Components: jboss-jstl-api
Environment: - JBoss EAP 7.0.8
- jboss-jstl-api_1.2_spec-1.1.3.Final
Reporter: Masafumi Miura
Assignee: Scott Marlow
Attachments: byteman-script.btm, example.zip
The following NullPointerException happens at ELEvaluator.parseExpressionString() due to a
concurrency issue.
Once this NPE happens, you will see same NPE every time when accessing the failed JSP. (If
development="true" is configured in <jsp-config>, recompile can happen in
the next access, so NPE can disappear after successful compilation in the next access.)
{code}
ERROR [io.undertow.request] (default task-4) UT005023: Exception handling request to
/dsl/g/clsys/cl/nop-constind/CNC001.jsp: org.apache.jasper.JasperException: JBWEB004001:
Unable to compile class for JSP
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:667)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:402)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:346)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
[jboss-servlet-api_3.1_spec-1.0.0.Final-redhat-1.jar:1.0.0.Final-redhat-1]
...(snip)...
...
Caused by: java.lang.NullPointerException
at
org.apache.taglibs.standard.lang.jstl.ELEvaluator.parseExpressionString(ELEvaluator.java:276)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at org.apache.taglibs.standard.lang.jstl.Evaluator.validate(Evaluator.java:71)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at
org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager.validate(ExpressionEvaluatorManager.java:131)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at
org.apache.taglibs.standard.tlv.el.ValidationUtil.validateExpression(ValidationUtil.java:26)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at
org.apache.taglibs.standard.tlv.el.JstlELCoreTLV.validateExpression(JstlELCoreTLV.java:26)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at
org.apache.taglibs.standard.tlv.JstlCoreTLV$Handler.startElement(JstlCoreTLV.java:158)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at
org.apache.xerces.parsers.AbstractSAXParser.startElement(AbstractSAXParser.java:498)
at
org.apache.xerces.parsers.AbstractXMLDocumentParser.emptyElement(AbstractXMLDocumentParser.java:180)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:275)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(XMLDocumentFragmentScannerImpl.java:1653)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:324)
at org.apache.xerces.parsers.XML11Configuration.parse(XML11Configuration.java:875)
at org.apache.xerces.parsers.XML11Configuration.parse(XML11Configuration.java:798)
at org.apache.xerces.parsers.XMLParser.parse(XMLParser.java:108)
at org.apache.xerces.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1198)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:564)
at org.apache.taglibs.standard.tlv.JstlBaseTLV.validate(JstlBaseTLV.java:158)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at org.apache.taglibs.standard.tlv.JstlCoreTLV.validate(JstlCoreTLV.java:97)
[jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
at org.apache.jasper.compiler.TagLibraryInfoImpl.validate(TagLibraryInfoImpl.java:552)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.compiler.Validator.validateXmlView(Validator.java:1856)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.compiler.Validator.validateExDirectives(Validator.java:1825)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:218)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:334)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:321)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:652)
[jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
... 61 more
{code}
-
https://github.com/jboss/jboss-jstl-api_spec/blob/jboss-jstl-api_1.2_spec...
{code}
252 public Object parseExpressionString(String pExpressionString)
253 throws ELException {
254 // See if it's an empty String
255 if (pExpressionString.length() == 0) {
256 return "";
257 }
258
259 if (!(mBypassCache) && (sCachedExpressionStrings == null)) {
260 createExpressionStringMap();
261 }
262
263 // See if it's in the cache
264 Object ret =
265 mBypassCache ?
266 null :
267 sCachedExpressionStrings.get(pExpressionString);
268
269 if (ret == null) {
270 // Parse the expression
271 Reader r = new StringReader(pExpressionString);
272 ELParser parser = new ELParser(r);
273 try {
274 ret = parser.ExpressionString();
275 if (!mBypassCache) {
276 sCachedExpressionStrings.put(pExpressionString, ret); // <- NPE
occurred at here
277 }
278 }
279 catch (ParseException exc) {
280 throw new ELException
281 (formatParseException(pExpressionString,
282 exc));
283 }
284 catch (TokenMgrError exc) {
285 // Note - this should never be reached, since the parser is
286 // constructed to tokenize any input (illegal inputs get
287 // parsed to <BADLY_ESCAPED_STRING_LITERAL> or
288 // <ILLEGAL_CHARACTER>
289 throw new ELException(exc.getMessage());
290 }
291 }
292 return ret;
293 }
{code}
-
https://github.com/jboss/jboss-jstl-api_spec/blob/jboss-jstl-api_1.2_spec...
{code}
~~~
51 /**
52 * The singleton instance of the evaluator *
53 */
54 static ELEvaluator sEvaluator =
55 new ELEvaluator
56 (new JSTLVariableResolver());
:
62 /**
63 * Translation time validation of an attribute value. This method
64 * will return a null String if the attribute value is valid;
65 * otherwise an error message.
66 */
67 public String validate(String pAttributeName,
68 String pAttributeValue) {
69 try {
70 sEvaluator.setBypassCache(true); // <-- mBypassCache is set to true
before invoking parseExpressionString()
71 sEvaluator.parseExpressionString(pAttributeValue);
72 sEvaluator.setBypassCache(false);
73 return null;
74 }
75 catch (ELException exc) {
{code}
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