How do you deal with people who badmouth friends?

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My team leader (kind of like my direct supervisor) got promoted so he handles a higher level team now. I on the other hand got moved to a different team. Sometimes, I would hear the higher level team people complain about my former team leader, how he's so bad, how he does this and that, even if he's just strictly following the company's policies. It's not as if he made those policies, he's just implementing them. They say things like, "could you get your team leader back? we don't like him!" and it annoys me to no end because I do want to have him as my boss again. My new boss doesn't do much. Unlike the old one, he sees to it that my pay will be correct every pay day, and that my career growth is steady. I don't really want to say anything whenever they start. I want to start defending him but I don't also want to be on their bad end since they're the support team. I don't want to tell my old boss what they've been saying either because I don't want to be the bad one. _