That seems like a quite significant (external) attack surface to add to the kernel? (With plans on adding more)
i for one am super excited that i have a much lighter weight option available. for example, on my/my parents openwrt wifi routers to expose files with, in a way that other computers in the house can use.
my fear of security holes is pretty weak. this will be exposed inside the firewall only (at least at first). and i trust that by promoting & moving such a thing into the kernel, we'll have a very involved active community trying to make sure things are safe. we'll notice & catch exploits quickly once they start to be used. the message here of fear & uncertainty does not resound with me. quite the opposite. sunlight is not perfect but it has proven to be a progressive & very adaptive means to disinfect & secure within cybersecurity.
edit: wow, -2, some strong disagreement! not sure what ya'll are so afraid of!! why so conservative? doesn't this seem like progress?
FWIW, these exploits are not all in legacy code. A recent SMB3 vulnerability "SMBGhost" used a lack of bounds checking of compressed data in the new SMB3 compression code, which can be triggered pre-auth.
If that bug is in a user space program, it's a bad bug, but you're at least not (unnecessarily!) opening up your entire kernel to RCE. Even assuming "many eyes find all bugs" some don't want to introduce the risk at all.