[dm-devel] [git pull] device mapper changes for 6.1

[Jason A. Donenfeld]

On Tue, Oct 18, 2022 at 11:54:49AM -0700, Linus Torvalds wrote:
> I think we have one major interface that is string-based (apart from
> the obvious pathname ones and the strings passed to 'execve()').
> 
> It's 'mount()' (and now fsconfig() etc), and it's string-based mainly
> because it has that nasty "arbitrary things that different filesystem
> may need for configuration"). And it has some nasty logging model
> associated with it too for output.
> 
> But no, we absolutely do *not* want to emulate that particular horror
> anywhere else.

This might ruin your day, but FYI, Netlink

   [...did you already run off screaming at the mention of Netlink?...]

Netlink has the whole "extack" extended acknowledgement mechanism, in
which netlink replies can and do contain error strings. Grep the kernel
for NL_SET_ERR_MSG and you'll see a bunch of these. (And as you
suggested, I wouldn't be surprised if some bad userspaces parse them.)

Jason