Function deregisterBroker Delete a Wrong Broker Without Close Broker

[byt3n33dl3]

Heyo, cool works, and awesome

is related to a potential memory management bug in the deregisterBroker function of a Kafka client implemented in Go. Let’s break it down step by step:

Here’s the function in question:

func (client *client) deregisterBroker(broker *Broker) {
	client.lock.Lock()
	defer client.lock.Unlock()

	_, ok := client.brokers[broker.ID()]
	if ok {
		Logger.Printf("client/brokers deregistered broker #%d at %s", broker.ID(), broker.Addr())
		delete(client.brokers, broker.ID())
		return
	}
	if len(client.seedBrokers) > 0 && broker == client.seedBrokers[0] {
		client.deadSeeds = append(client.deadSeeds, broker)
		client.seedBrokers = client.seedBrokers[1:]
	}
}

What’s the issue?

Problem Source: Using a Pointer (*Broker) as Parameter

• The parameter broker *Broker is a pointer.
• Even if two brokers have the same ID(), they may be different pointers in memory.

// Different pointers, same broker ID
b1 := &Broker{id: 1}
b2 := &Broker{id: 1} // same ID but different memory

The Bug:

• client.brokers is a map from broker.ID() to *Broker. The function uses the ID to delete from the map:
  • delete(client.brokers, broker.ID())
• This removes the key from the map, but not necessarily the correct pointer if two brokers have the same ID.
• Also, there's no call to broker.Close() or similar cleanup so the memory (or any active connections/resources) held by the broker aren't released.

Summary of What’s wrong? Deregistering a broker by ID may remove the wrong broker (due to pointer mismatch), leaving the actual broker unclosed in memory. Cause Broker is passed as a pointer; broker with same ID might be a different object in memory.