Need

Proper management of resources to prevent memory leaks

Context

• Usage of Ruby 2.0+ for developing Ruby applications
• Usage of Rails framework for building web applications

Description

Non compliant code

        def create
  user = User.new(user_params)
  if user.save
    render json: user, status: :created
  else
    render json: user.errors, status: :unprocessable_entity
  end
end
        
        

The above code is an example of a function within a Ruby on Rails controller that creates a new user. It takes in parameters for the user ( user_params), attempts to save them to the database, and then either returns the newly created user or the errors that occurred.

The vulnerability here is that there is no explicit release of the user object after it has been used. In Ruby, garbage collection is supposed to handle this automatically, but in some cases, especially when dealing with larger objects or when the system is under heavy load, this may not happen immediately or at all, leading to a memory leak. This can cause the system to consume more and more memory over time, eventually leading to performance issues or even system crashes if the memory is not released.

The problem is exacerbated if the create function is called frequently, such as in a high-traffic web application, as this can lead to a large number of user objects being created and not released, consuming a significant amount of memory.

This is an example of the "Improper resource allocation
- Memory leak" vulnerability, as the system does not properly manage the memory resources allocated for the user objects.

Steps

• Explicitly release resources after they are no longer needed
• Ensure that all opened resources are properly closed or deallocated
• Use appropriate programming patterns and language features to manage resource allocation and deallocation
• Implement proper error handling and cleanup mechanisms to handle exceptions and errors

Compliant code

        def create
  user = User.new(user_params)
  if user.save
    render json: user, status: :created
  else
    render json: user.errors, status: :unprocessable_entity
  end
  user = nil
end
        
        

The updated code includes a line at the end of the create method that explicitly sets the user variable to nil. This is a way of manually deallocating the memory that was used to store the user object.

In Ruby, memory management is handled by the garbage collector, which automatically frees up memory that is no longer in use. However, in some cases, it may be necessary to manually deallocate memory to ensure that resources are freed up as soon as they are no longer needed. This is especially important in a web application, where many requests are being processed concurrently and memory leaks can quickly lead to performance issues.

By setting user to nil, we are explicitly telling Ruby that the user object is no longer needed and its memory can be freed. This helps to prevent memory leaks and ensure that our application is using resources efficiently.

It's important to note that this is just one part of a comprehensive approach to resource management. We should also ensure that all opened resources are properly closed, use appropriate programming patterns and language features to manage resource allocation and deallocation, and implement proper error handling and cleanup mechanisms to handle exceptions and errors.

References

• 317. Improper resource allocation - Memory leak