1. Vulnerability Description

• Self-assignment means that an object computes itself.
• There is a risk of multiple references that refer to one object in several places and may cause a crash.

2. Vulnerability Countermeasure

• If you have a function with multi-parameter, It is necessary to check whether the function works normally when each parameter is the same.

3. Sample Code

• Vulnerable Code

Window& Window::operator=(const Window& rhs)
{
    delete sb;
    sb = new ScrollBar(*rhs.sb);
    return *this;
}

• Safe Code

Window& Window::operator=(const Window& rhs)
{
    // Check that it is self-assignment
    if (this == &rhs;)
	return *this;
    // Make sure to copy it because throw can occur after delete.
    ScrollBar *sbOld = sb;
    sb = new ScrollBar(*rhs.sb);
    delete sbOld;
    return *this;
}