Linux ABI and permissions to /dev

Under latest RELENG_5 I'm experiencing since recently (about 2-4 weeks I
think) "permission denied" errors under the Linux ABI on write-access to
e.g. /dev/null or other devices under /dev:

| $ id
| uid=10000(rse) gid=10000(rse) groups=10000(rse),5(operator),2001(en)
| $ ls -l /dev/null
| crw-rw-rw-  1 root  wheel    2,   2 Oct 15 21:39 /dev/null
| $ echo foo >/dev/null
| $ ls -l /compat/linux/bin/dev/null
| ls: /compat/linux/bin/dev/null: No such file or directory
| $ /compat/linux/bin/bash
| bash   bash2
| $ /compat/linux/bin/bash
| $ ls -l /dev/null
| crw-rw-rw-    1 root     wheel      2,   2 Oct 15 21:40 /dev/null
| $ echo foo >/dev/null
| bash: /dev/null: Permission denied
| $

Has anybody an idea where to search? There were no changes to devfs
recently and the recent changes to the Linuxulator seemed harmless to me
at the first glance...
                                       Ralf S. Engelschall
                                       rse_at_engelschall.com
                                       www.engelschall.com