StringUtil.upperCaseFirstLetter can cause ArrayIndexOutOfBoundsException

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.3.10 DXP FP2, 7.3.10.3 DXP SP3, 7.4.13 DXP U15, Master
• Fix Version/s: 7.0.X, 7.1.X, 7.2.10 DXP FP18, 7.2.X, 7.3.X, 7.4.3.18 CE GA18, 7.4.3.21 CE GA21, 7.4.3.22 CE GA22, Master
• Component/s: Core Infrastructure
• Labels:
  • 7.4-known-issues
  • backend_test
  • ee-ts
  • liferay-fixpack-dxp-18-7210
  • liferay-fixpack-dxp-27-7110
  • liferay-fixpack-dxp-4-7310
  • liferay-update-dxp-18-7413
  • liferay-update-dxp-4-7310
• Branch Version/s:
  7.3.x, 7.2.x, 7.1.x, 7.0.x
• Backported to Branch:
  Committed
• Fix Priority: 4
• Git Pull Request: https://github.com/liferay-core-infra/liferay-portal/pull/492

Open scripting console:

try {
out.println("'" + com.liferay.portal.kernel.util.StringUtil.upperCaseFirstLetter("") + "'");
}
catch(Throwable t) {
t.printStackTrace(out);
} 

Run the script.

Expected result

''

Actual result, stacktrace.

java.lang.ArrayIndexOutOfBoundsException: 0
	at com.liferay.portal.kernel.util.StringUtil.upperCaseFirstLetter(StringUtil.java:4659)
	at com.liferay.portal.kernel.util.StringUtil$upperCaseFirstLetter.call(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
...

Real-world stacktrace with Liferay DXP 7.3 fp2

2022-03-18 11:17:25.102 ERROR [http-nio-10080-exec-11][render_portlet_jsp:131] null
java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0
        at com.liferay.portal.kernel.util.StringUtil.upperCaseFirstLetter(StringUtil.java:4659)
        at com.liferay.dynamic.data.mapping.internal.util.DDMIndexerImpl.getValueFieldName(DDMIndexerImpl.java:436)
        at com.liferay.dynamic.data.mapping.internal.util.DDMIndexerImpl.createDDMStructureFieldSort(DDMIndexerImpl.java:201)
        at com.liferay.dynamic.data.mapping.internal.util.DDMIndexerImpl.createDDMStructureFieldSort(DDMIndexerImpl.java:260)
        at com.liferay.asset.internal.util.AssetHelperImpl._getSearchSort(AssetHelperImpl.java:595)
        at com.liferay.asset.internal.util.AssetHelperImpl._getSearchSorts(AssetHelperImpl.java:619)
        at com.liferay.asset.internal.util.AssetHelperImpl._getAssetSearcher(AssetHelperImpl.java:562)
        at com.liferay.asset.internal.util.AssetHelperImpl.searchAssetEntries(AssetHelperImpl.java:483)
        at com.liferay.asset.internal.util.AssetHelperImpl.searchAssetEntries(AssetHelperImpl.java:462)
        at com.liferay.asset.publisher.web.internal.util.AssetPublisherHelperImpl.getAssetEntries(AssetPublisherHelperImpl.java:147)
        at com.liferay.asset.publisher.web.internal.util.AssetPublisherHelperImpl._getAssetEntryResultsByDefault(AssetPublisherHelperImpl.java:1021)
        at com.liferay.asset.publisher.web.internal.util.AssetPublisherHelperImpl.getAssetEntryResults(AssetPublisherHelperImpl.java:485)
        at com.liferay.asset.publisher.web.internal.display.context.AssetPublisherDisplayContext.getAssetEntryResults(AssetPublisherDisplayContext.java:447)
        at org.apache.jsp.view_jsp._jspService(view_jsp.java:697)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:411)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:473)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:377)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
2022-03-18 11:17:25.107 ERROR [http-nio-10080-exec-17][render_portlet_jsp:131] null