Page can be set as its own parent page, resulting in data corruption

I have had a user report a problem with a page he updated. After investigation, I suspect he fell victim to the following bug, which I was able to reproduce in a test space.

Here is the scenario and the expected behavior:
1. start with an existing page
2. bring up the page update screen
3. enter the name of the page in the page's parent page field
4. save ('update')
5. EXPECT: validation error indicating that a page cannot be its own parent
6. reenter the name of the page in the parent page field, but this time with a different case
7. EXPECT: validation error indicating that a page cannot be its own parent

In reality however, while expectation 5 is met (" The page itself can not be set as its own parent page."), expectation 7 fails and the page is saved.
Because page name uniqueness in Confluence is on a case-insensitive basis (even though the case is preserved), the resulting page is in effect pointing to itself as its own parent. Unsurprisingly trying to access the page causes the system error below (stack overflow due to infinite recursion in the Page.getAncestry() method).

Beside needing the defect to be fixed (to avoid future page corruption), I also need help restoring the affected user pages to a working order. Or will I have to ask them to recreate the pages by hand?

Cause:
org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getAncestry' in class com.atlassian.confluence.pages.Page threw exception class java.lang.StackOverflowError : null

Stack Trace: [hide]

org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getAncestry' in class com.atlassian.confluence.pages.Page threw exception class java.lang.StackOverflowError : null
at org.apache.velocity.runtime.parser.node.PropertyExecutor.execute(PropertyExecutor.java:188)
at org.apache.velocity.runtime.parser.node.ASTIdentifier.execute(ASTIdentifier.java:226)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:207)
at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:357)
at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:135)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:94)
at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:109)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:271)
at org.apache.velocity.runtime.directive.Parse.render(Parse.java:232)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:153)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:271)
at org.apache.velocity.Template.merge(Template.java:296)
at com.opensymphony.webwork.dispatcher.VelocityResult.doExecute(VelocityResult.java:91)
at bucket.util.profiling.ProfiledVelocityResult.doExecute(ProfiledVelocityResult.java:18)
at com.opensymphony.webwork.dispatcher.WebWorkResultSupport.execute(WebWorkResultSupport.java:116)
at com.opensymphony.xwork.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:263)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:187)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.intercept(DefaultWorkflowInterceptor.java:55)
at com.atlassian.confluence.core.ConfluenceWorkflowInterceptor.intercept(ConfluenceWorkflowInterceptor.java:33)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.atlassian.confluence.core.ConfluenceValidationInterceptor.intercept(ConfluenceValidationInterceptor.java:16)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.security.actions.PermissionCheckInterceptor.intercept(PermissionCheckInterceptor.java:40)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.pages.actions.PageAwareInterceptor.intercept(PageAwareInterceptor.java:73)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.core.ConfluenceAutowireInterceptor.intercept(ConfluenceAutowireInterceptor.java:25)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.user.actions.AuthenticatedUserInterceptor.intercept(AuthenticatedUserInterceptor.java:51)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.util.XWorkTransactionInterceptor.intercept(XWorkTransactionInterceptor.java:133)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:115)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:229)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:199)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:432)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:356)
at com.atlassian.confluence.servlet.simpledisplay.SimpleDisplayServlet.doGet(SimpleDisplayServlet.java:44)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:118)
at com.atlassian.confluence.util.profiling.ProfilingPageFilter.parsePage(ProfilingPageFilter.java:159)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:168)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:181)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:170)
at bucket.custom.FlushingSpringSessionInViewFilter.doFilterInternal(FlushingSpringSessionInViewFilter.java:30)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:73)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
at com.atlassian.confluence.util.error.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:27)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:36)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2422)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:163)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:199)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:828)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:700)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:584)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Thread.java:534)

Referer URL: http://confluence/dashboard.action

Build Information:
Uptime: 7 minutes, 23 seconds
Version: 1.3.5
Build Number: 122

Server Information:
Application Server: Apache Tomcat/4.1.30
Servlet Version: 2.3
Database Dialect: net.sf.hibernate.dialect.HSQLDialect

Memory Information:
Total Memory: 587 MB
Free Memory: 228 MB
Used Memory: 359 MB

System Information:
System Date: Wednesday, 14 Dec 2005
System Time: 12:18:29
System Favourite Colour: Lime
Java Version: 1.4.2_04
Java Vendor: Sun Microsystems Inc.
JVM Version: 1.0
JVM Vendor: Sun Microsystems Inc.
JVM Implementation Version: 1.4.2_04-b05
Java Runtime: Java(TM) 2 Runtime Environment, Standard Edition
Java VM: Java HotSpot(TM) Client VM
User Name: dev_build
User Timezone: America/New_York
Operating System: Windows 2003 5.2
OS Architecture: x86
Request

Information:
URL: http://confluence/display/sandbox/Test+Child+Page+1.2

• Scheme: http
• Server: confluence
• Port: 80
• URI: /500page.jsp
• - Context Path:
• - Servlet Path: /500page.jsp
• - Path Info: null
• - Query String: null

Attributes:

• javax.servlet.error.exception : org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getAncestry' in class com.atlassian.confluence.pages.Page threw exception class java.lang.StackOverflowError : null
• javax.servlet.error.message :
• os_securityfilter_already_filtered : true
• com.atlassian.johnson.filters.JohnsonFilter_already_filtered : true
• _sitemesh_using_stream : false
• javax.servlet.error.request_uri : /display/sandbox/Test+Child+Page+1.2
• javax.servlet.error.status_code : 500
• _sitemesh_filterapplied : true
• javax.servlet.error.servlet_name : simple-display
• webwork.valueStack : com.opensymphony.xwork.util.OgnlValueStack@c81bd9
• loginfilter.already.filtered : true
• atlassian.core.seraph.original.url : /display/sandbox/Test+Child+Page+1.2
• javax.servlet.jsp.jspException : org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getAncestry' in class com.atlassian.confluence.pages.Page threw exception class java.lang.StackOverflowError : null
• sessioninview.FILTERED : true

Parameters:

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