Linux 4.5-rc5: efivarfs fixed to avoid “rm -rf /” bricking UEFI

For context, this is in reference to a bug that was discussed a couple weeks ago: https://news.ycombinator.com/item?id=10999335

  Systemd mounted efivarfs read-write, allowing motherboard bricking via 'rm' 

Essentially, systemd defaulted to a configuration where the computer's motherboard could be permanently destroyed by removing a 'file' from the command line. The bug reporter argued that this was unduly dangerous, but the systemd developers thought that systemd was working as intended.

Here's a reasonably impartial discussion on a FreeBSD list that gives an overview: https://forums.freebsd.org/threads/54951/

And from that thread, here's a link to Matthew Garrett (the creator of efivarfs) saying that efivarfs is at fault here rather than systemd: https://twitter.com/mjg59/status/693494314941288448

> but the developer's thought that it was working as intended

Really? Is that evidenced by Lennart's response to this, which stated "The ability to hose a system is certainly reason enought to make sure it's well protected and only writable to root."[1]? I think it implies the opposite.

1: https://github.com/systemd/systemd/issues/2402

Root is certainly capable, traditionally, of completely hosing all levels of the software stack. Usually it's the OS's job to protect even root from being able to hose hardware/firmware, especially by easy-to-make mistake.