Brazil is one of the most strict countries when it comes to providing proof of onward (leaving ticket from brazil) If you wish to come to Brazil on a one-way ticket like a real boss and stay there for time you gotta bring ticket proof of leaving brazil. If you don't bring the airport may deny your boarding get proof of ticket and hotel beforehand.
São Paulo Guarulhos Airport – IATA Code – GRU.
São Paulo Congonhas Airport – IATA Code – CGH.
Brasília Airport – IATA Code – BSB.
Rio de Janeiro Galeão Airport – IATA Code – GIG.
Brazil is strict. You want to bring a return to avoid denying your flight and sending you home. Get your shit together and bring a ticket to avoid a problem.