Re: kern/56232: Unstable system with tar on /dev

[RVP <rvp%SDF.ORG@localhost>]

The following reply was made to PR kern/56232; it has been noted by GNATS.

From: RVP <rvp%SDF.ORG@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/56232: Unstable system with tar on /dev
Date: Fri, 4 Jun 2021 06:56:00 +0000 (UTC)

 Caused by, at least, pad(4), and possibly, lua(4):
 
 $ id
 uid=1001(rvp) gid=1001(rvp) groups=1001(rvp),0(wheel),9(wsrc)
 $ sudo chmod go-rw /dev/pad* /dev/lua*
 $ tar -C /dev -cf /dev/null .
 tar: Couldn't list extended attributes: Permission denied
 tar: Couldn't list extended attributes: Invalid argument
 ...
 $ dmesg | tail
 [     6.059407] intelfb0 at i915drmkms0
 [     6.059407] intelfb0: framebuffer at 0xe0364000, size 1366x768, depth 
 32, stride 5504
 [     6.789401] wsdisplay0 at intelfb0 kbdmux 1: console (default, vt100 
 emulation), using wskbd0
 [     6.799401] wsmux1: connecting to wsdisplay0
 [    14.529371] wsdisplay0: screen 1 added (default, vt100 emulation)
 [    14.539372] wsdisplay0: screen 2 added (default, vt100 emulation)
 [    14.539372] wsdisplay0: screen 3 added (default, vt100 emulation)
 [    14.539372] wsdisplay0: screen 4 added (default, vt100 emulation)
 [    20.379350] cpu 0: ucode 0x15->0x21
 [    20.389352] cpu 1: ucode 0x15->0x21
 $
 
 No errors reported by the kernel if read perms. are removed from
 /dev/pad*, /dev/lua*
 
 Issues I noticed:
 
 - In sys/dev/pad/pad.c, padattach() doesn't seem to be called from 
 anywhere
    and therefore mutex_init() is never called.
 
    `pad_ca' is used in 2 places, but is defined nowhere.
 
 - Similarly, in sys/net/if_tap.c, tapattach() is not called by anybody.
 
 
 -RVP