[WW-4062] Invalid OGNL expressions are not cached

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.3.14
• Fix Version/s: 6.5.0
• Component/s: Value Stack
• Assignee: Unassigned
• Reporter: Saulius Tvarijonas
• Created: 29/Apr/13 09:37
• Updated: 06/Apr/24 16:46

Description

I am using velocity to render results page. During performance optimizations I noticed significant memory usage from com.opensymphony.xwork2.ognl.OgnlUtil#compile. There is caching implemented in OgnlUtil, but if expression compilation fails, it is not cached.
I am not really sure if this problem is in struts or velocity engine. But situation is following:

1. In velocity template trying to render string <p>$!foo</p>
2. If value is null, velocity calls org.apache.velocity.runtime.parser.node.ASTReference#getNullString
3. Internally there is call to context.get(".literal." + nullString)
4. And this ".literal." expression always reaches OgnlUtil#compile and compilation fails.

Below is stacktrace for more details:

at com.opensymphony.xwork2.ognl.OgnlUtil.compile(OgnlUtil.java:248)
at com.opensymphony.xwork2.ognl.OgnlUtil.getValue(OgnlUtil.java:236)
at com.opensymphony.xwork2.ognl.OgnlValueStack.getValueUsingOgnl(OgnlValueStack.java:291)
at com.opensymphony.xwork2.ognl.OgnlValueStack.tryFindValue(OgnlValueStack.java:274)
at com.opensymphony.xwork2.ognl.OgnlValueStack.tryFindValueWhenExpressionIsNotNull(OgnlValueStack.java:256)
at com.opensymphony.xwork2.ognl.OgnlValueStack.findValue(OgnlValueStack.java:236)
at com.opensymphony.xwork2.ognl.OgnlValueStack.findValue(OgnlValueStack.java:298)
at org.apache.struts2.dispatcher.StrutsRequestWrapper.getAttribute(StrutsRequestWrapper.java:82)
at org.apache.velocity.tools.view.context.ChainedContext.getAttribute(Unknown Source:-1)
at org.apache.velocity.tools.view.context.ChainedContext.internalGet(Unknown Source:-1)
at org.apache.velocity.context.AbstractContext.get(AbstractContext.java:193)
at org.apache.velocity.context.InternalContextAdapterImpl.get(InternalContextAdapterImpl.java:267)
at org.apache.velocity.runtime.parser.node.ASTReference.getNullString(ASTReference.java:510)
at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:465)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
at org.apache.velocity.runtime.parser.node.ASTStringLiteral.value(ASTStringLiteral.java:330)
at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:71)
at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:142)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
at org.apache.velocity.runtime.directive.Parse.render(Parse.java:260)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
at org.apache.velocity.Template.merge(Template.java:356)
at org.apache.velocity.Template.merge(Template.java:260)
at org.apache.struts2.dispatcher.VelocityResult.doExecute(VelocityResult.java:156)
at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)