Ask HN: Internships working on C or C++ FOSS software?

I'm a second year college student and admittedly I've started applying to internships pretty late. In my past experience, professional or otherwise, I've done mostly web dev and want to move away from that. I've used C++ and, more recently, C in uni projects and would like to use those skills to contribute to some interesting FOSS projects, e.g. the Linux kernel, LLVM, PostgreSQL. Unfortunately the development for many of these things seems to be divided between many different companies and volunteers so it's unclear where to apply if I wanted to start working on any project in particular. Could I get any recommendations for companies that still have internships open which might have me working on that kind of thing? I've applied to one such position at Red Hat but am not having an easy time finding others.