robsware

The vulnerability is NULL Pointer Dereference

csharp
// Vulnerable code
class Program
{
    static void Main(string[] args)
    {
        string firstName = null;
        string lastName = "Smith";

        int nameLength = firstName.Length + lastName.Length;
        Console.WriteLine("Full name length: " + nameLength);
    }
}

csharp // Vulnerable code class Program { static void Main(string[] args) { string firstName = null; string lastName = "Smith"; int nameLength = firstName.Length + lastName.Length; Console.WriteLine("Full name length: " + nameLength); } } In the vulnerable code, the `firstName` variable is initialized as null, so when the program tries to access its `Length` property, it causes a NullReferenceException. To fix the issue, we use the null conditional (`?.`) operator when accessing the Length property for both `firstName` and `lastName`. This helps to avoid the exception from occurring. If the value is null, we use the null coalescence (`??`) operator to assign 0 as the default value for the length. This ensures that the nameLength calculation can proceed safely even if either firstName or lastName are null.

csharp
// Solution how to fix the vulnerable code
class Program
{
    static void Main(string[] args)
    {
        string firstName = null;
        string lastName = "Smith";

        int firstNameLength = firstName?.Length ?? 0;
        int lastNameLength = lastName?.Length ?? 0;

        int nameLength = firstNameLength + lastNameLength;
        Console.WriteLine("Full name length: " + nameLength);
    }
}