int mlx4_register_mac(struct mlx4_dev *dev, u8 port, u64 mac, int *index)
{
	struct mlx4_mac_table *table = &mlx4_priv(dev)->port[port].mac_table;
	int i, err = 0;
	int free = -1;

	mlx4_dbg(dev, "Registering MAC: 0x%llx\n", (unsigned long long) mac);
	mutex_lock(&table->mutex);
	for (i = 0; i < MLX4_MAX_MAC_NUM - 1; i++) {
		if (free < 0 && !table->refs[i]) {
			free = i;
			continue;
		}

		if (mac == (MLX4_MAC_MASK & be64_to_cpu(table->entries[i]))) {
			/* MAC already registered, increase refernce count */
			*index = i;
			++table->refs[i];
 			goto out;
 		}
 	}
 	mlx4_dbg(dev, "Free MAC index is %d\n", free);
 
 	if (table->total == table->max) {
		/* No free mac entries */
		err = -ENOSPC;
		goto out;
	}

	/* Register new MAC */
	table->refs[free] = 1;
	table->entries[free] = cpu_to_be64(mac | MLX4_MAC_VALID);

	err = mlx4_set_port_mac_table(dev, port, table->entries);
	if (unlikely(err)) {
		mlx4_err(dev, "Failed adding MAC: 0x%llx\n", (unsigned long long) mac);
		table->refs[free] = 0;
		table->entries[free] = 0;
		goto out;
	}

	*index = free;
	++table->total;
out:
	mutex_unlock(&table->mutex);
	return err;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.