Code Correctness: Stack Exhaustion

A program capable of creating a circular link in a data structure can cause stack exhaustion when the data structure is processed recursively.

Using recursion is a staple for creating and managing linked data structures. Recursion also runs the risk of processing indefinitely if the data incorporates a circular link, which in turn will exhaust the stack and crash the program.

Example 1: The following code snippet demonstrates this vulnerability using Apache Log4j2.

Marker child = MarkerManager.getMarker("child");
Marker parent = MarkerManager.getMarker("parent");

child.addParents(parent);
parent.addParents(child); 
        
String toInfinity = child.toString();

When child calls toString(), which includes a recursive processing method, it triggers a stack overflow exception (stack exhaustion). This exception occurs due to the circular link between child and parent.