OK, I actually asked a kernel dev friend about this because it affects my work on sandstorm.io, and he says that defense against malicious filesystems is in fac

OK, I actually asked a kernel dev friend about this because it affects my work on sandstorm.io, and he says that defense against malicious filesystems is in fact something Theodore Ts'o, the ext4 maintainer (and Googler), cares deeply about. Awesome! Now, that doesn't automatically mean it's safe, but given this new piece of information, I'd say that the case for removing ext4 for attack surface reasons is significantly weakened.