Ok, assuming you've undone the damage to /lib/udev/devices/null, could you please reboot your machine until you have a /dev/null with only 0600 permissions.
Could you note whether it takes any longer to boot than usual?
From that boot, please attach /var/log/udev
Also please run "udevtest /class/mem/null"
Ok, assuming you've undone the damage to /lib/udev/ devices/ null, could you please reboot your machine until you have a /dev/null with only 0600 permissions.
Could you note whether it takes any longer to boot than usual?
From that boot, please attach /var/log/udev
Also please run "udevtest /class/mem/null"