get_word and get_quoted_word, at the very least, are currently quite fragile -- they're expecting short subjects, which won't necessarily be the case. This can be easily seen by reverting the parts of r359689 that doubled the line buffer sizes and observing the new output to stderr as it tries to parse too long of lines. Previously, we just clobbered memory past the line buffer and did the wrong thing. r359689 was just a band-aid, though -- these sizes will need adjusted as needs change and randomly blow up on valid config bits. It would be nicer/more developer friendly to be more dynamic here.
https://reviews.freebsd.org/D24373
A commit references this bug: Author: jah Date: Sun Apr 12 02:42:42 UTC 2020 New revision: 359815 URL: https://svnweb.freebsd.org/changeset/base/359815 Log: config(8): use sbuf to manage line buffers PR: 245476 Reported by: kevans Reviewed by: imp, kevans MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D24373 Changes: head/usr.sbin/config/main.c