1. Vulnerability Description

• If the same member field is accessed simultaneously, data race can occur.

2. Vulnerability Countermeasure

• Access member fields using synchronized keywords, atomic objects, and volatile keywords
• Access from the same thread using @MainThread or @ThreadConfined를

3. Sample Code

• Vulnerable Code
  • Unexpected results may occur if multiple threads use the setMemory method in the following calculator classes :

...
public class Calculator {
	private int memory;
	
	public int getMemory(){
		return memory;
	}
	
	public void setMemory(int memory){
		this.memory = memory;
		try{
			Thread.sleep(2000);
		}catch(InterruptedException e){}
		
		System.out.println(Thread.currentThread().getName() + "": "" + this.memory);
	}
}
...

• Safe Code
  • Add a synchronized keyword so that no other thread can execute when setting memory

...
public class Calculator {
	private int memory;
	
	public int getMemory(){
		return memory;
	}
	
	public synchronized void setMemory(int memory){
		this.memory = memory;
		try{
			Thread.sleep(2000);
		}catch(InterruptedException e){}
		
		System.out.println(Thread.currentThread().getName() + "": "" + this.memory);
	}
}
...