Ubuntu
udev package

/dev/null permission

Bug #58509 reported by danielpf
2
Affects Status Importance Assigned to Milestone
udev (Ubuntu)
Fix Released
High
Scott James Remnant (Canonical)

Bug Description

I met twice the situation that Kubuntu dapper sets /dev/null to permission

Crw-----------

so when starting X for example the script fails because somewhere permission to write on /dev/null is required.

The problem is fixed if root sets the permission to

chmod a+rw /dev/null

Revision history for this message
Micah Cowan (micahcowan) wrote :

RawSewage_ on #ubuntu+1 was having this problem, so I'll Confirm it.

Revision history for this message
Michael Hirsch (mdhirsch) wrote :

This happens to me, too. This is pretty critical because the permission seem to get reset to 600 after a reboot, so X never starts up successfully.

Revision history for this message
danielpf (danielpf) wrote :

Just for those meeting this problem, here is my procedure to login.
A better one would be to find which script sets /dev/null to crw------ just after boot!

After booting, when the login screen appears, I type Alt+Ctrl+F1 to get a console.
Then I login as user and:

$ sudo chmod a+rw /dev/null

Since I have a non us keyboard I have to remember the position for + and / on a us keyboard.

Then I return to the X screen with Alt+Ctrl+F7 and can login.

Revision history for this message
Jimmy the shoe (jdshewey) wrote :

I can also confirm on kubuntu dapper. Permissions also get reset after reboot like Michael Hirsch. Also, I checked /etc/udev/rules.d/40-permissions.rules and have 'KERNEL=="null", MODE="0666"' as it should be.

Revision history for this message
danielpf (danielpf) wrote : Re: [Bug 58509] Re: /dev/null permission

I have found that the problem lies in the udev package, which has
/lib/udev/devices/null
set to the wrong permission.
Just change the permission of this file to a+rw and at the next boot
/dev/null
will have the same permission.

Daniel

On 9/20/06, Jimmy the shoe <email address hidden> wrote:
>
> I can also confirm on kubuntu dapper. Permissions also get reset after
> reboot like Michael Hirsch. Also, I checked
> /etc/udev/rules.d/40-permissions.rules and have 'KERNEL=="null",
> MODE="0666"' as it should be.
>
> --
> /dev/null permission
> https://launchpad.net/bugs/58509
>

Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote :

PLEASE IGNORE THE PREVIOUS COMMENT!

DO NOT ALTER THE PERMISSION OF /lib/udev/devices/null

IF YOU HAVE DONE SO, PLEASE PUT IT BACK TO 0600

Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote :

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"

Changed in udev:
assignee: nobody → keybuk
importance: Undecided → High
status: Confirmed → Needs Info
Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote :

Have just read this bug properly -- and I note all the problems are with dapper. This problem has been fixed and should not occur in edgy.

Changed in udev:
status: Needs Info → Fix Released
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