udev-140 Bug: udevadm test changing mode of /dev to 660, so making /dev unusuable for users

[Matthias Schwarzott <zzam@gentoo.org>]

Hi there!

This time I have a very strange error. I tried what happens when using
# udevadm test /sys/class/mem/null

and strange, a bit later some user processes had problems accessing /dev/null.
A quick check showed, that the permissions of /dev were destroyed.

# ls -ld /dev /dev/null
drw-rw---- 16 root root 4280 18. Mär 11:14 /dev
crw-rw-rw-  1 root root 1, 3 17. Mär 08:05 /dev/null

Changing it back to 775 and retrying showed, that it must be udevadm test that 
destroys it.

# ls -ld /dev /dev/null
drwxrwxr-x 16 root root 4280 18. Mär 11:05 /dev
crw-rw-rw-  1 root root 1, 3 17. Mär 08:05 /dev/null

# udevadm test /sys/class/mem/null/
run_command: calling: test
udevadm_test: version 140
This program is for debugging only, it does not run any program,
specified by a RUN key. It may show incorrect results, because
some values may be different, or not available at a simulation run.

parse_file: reading '/dev/.udev/rules.d/10-root-link.rules' as rules file
parse_file: reading '/etc/udev/rules.d/15-em8300.rules' as rules file
parse_file: reading '/lib/udev/rules.d/30-kernel-compat.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-alsa.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-gentoo.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-isdn.rules' as rules file
parse_file: reading '/etc/udev/rules.d/40-lomoco.rules' as rules file
parse_file: reading '/etc/udev/rules.d/48-qemu.rules' as rules file
parse_file: reading '/lib/udev/rules.d/50-firmware.rules' as rules file
parse_file: reading '/lib/udev/rules.d/50-udev-default.rules' as rules file
parse_file: reading '/etc/udev/rules.d/55-usbirboy.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-cdrom_id.rules' as rules file
parse_file: reading '/etc/udev/rules.d/60-pcmcia.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-input.rules' as rules 
file
parse_file: reading '/lib/udev/rules.d/60-persistent-serial.rules' as rules 
file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage-tape.rules' as 
rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage.rules' as rules 
file
parse_file: reading '/lib/udev/rules.d/60-persistent-v4l.rules' as rules file
parse_file: reading '/etc/udev/rules.d/60-virtualbox.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-persistent-storage-edd.rules' as 
rules file
parse_file: reading '/etc/udev/rules.d/64-device-mapper.rules' as rules file
parse_file: reading '/etc/udev/rules.d/64-md-raid.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-bluetooth-pcmcia.rules' as rules 
file
parse_file: reading '/etc/udev/rules.d/70-bluetooth.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-libgphoto2.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-libsane.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-persistent-cd.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-persistent-net.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-cd-aliases-generator.rules' as rules 
file
parse_file: reading '/lib/udev/rules.d/75-persistent-net-generator.rules' as 
rules file
parse_file: reading '/lib/udev/rules.d/79-fstab_import.rules' as rules file
parse_file: reading '/lib/udev/rules.d/80-drivers.rules' as rules file
parse_file: reading '/etc/udev/rules.d/90-hal.rules' as rules file
parse_file: reading '/lib/udev/rules.d/90-network.rules' as rules file
parse_file: reading '/etc/udev/rules.d/90-zzam.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-udev-late.rules' as rules file
parse_file: reading '/etc/udev/rules.d/99-fuse.rules' as rules file
parse_file: reading '/etc/udev/rules.d/99-iscan.rules' as rules file
udev_rules_new: rules use 94332 bytes tokens (7861 * 12 bytes), 14704 bytes 
buffer
udev_rules_new: temporary index used 31800 bytes (1590 * 20 bytes)
udev_device_new_from_syspath: device 0x8d120c0 has devpath '/class/mem/null/'
udev_device_new_from_syspath: device 0x8d122c8 has devpath '/class/mem/null/'
udev_device_read_db: device 0x8d122c8 filled with db symlink data '/dev/'
udev_rules_apply_to_event: 
LINK 'char/1:3' /lib/udev/rules.d/50-udev-default.rules:5
udev_device_new_from_syspath: device 0x8d125e0 has 
devpath '/devices/virtual/mem/null'
udev_rules_apply_to_event: 
RUN 'socket:/org/freedesktop/hal/udev_event' /etc/udev/rules.d/90-hal.rules:2
udev_rules_apply_to_event: 
RUN 'socket:@/org/kernel/udev/monitor' /lib/udev/rules.d/95-udev-late.rules:7
udev_event_execute_rules: no node name set, will use kernel name ''
udev_device_update_db: create db link ( char/1:3)
udev_node_add: creating device node '/dev/', devnum=1:3, mode\x0660, uid=0, 
gid=0
udev_node_mknod: atomically replace existing file '/dev/'
udev_node_mknod: rename(/dev/.udev-tmp, /dev/) failed: Invalid cross-device 
link
udev_node_mknod: chmod(/dev/, 020660)
udev_node_mknod: chown(/dev/, 0, 0)
update_link: found 2 devices with name '/dev/char/1:3'
udev_device_new_from_syspath: device 0x8d12878 has 
devpath '/devices/virtual/mem/null'
udev_device_read_db: device 0x8d12878 filled with db symlink data '/dev/null'
update_link: '/dev/char/1:3' with target '/dev/' has the highest priority 0, 
create it
node_symlink: atomically replace '/dev/char/1:3'
udevadm_test: run: 'socket:/org/freedesktop/hal/udev_event'
udevadm_test: run: 'socket:@/org/kernel/udev/monitor'

# ls -ld /dev /dev/null
drw-rw---- 16 root root 4280 18. Mär 11:14 /dev
crw-rw-rw-  1 root root 1, 3 17. Mär 08:05 /dev/null

So it does something strange, maybe some rules are corrupt or misinterpreted.

Regards
Matthias