Re: [Security-Discuss] [ MDKSA-2006:086 ] - Don't update the kernel on Soft-RAID-Sytems

On Sun, 21 May 2006, Luca Berra wrote:

> On Sun, May 21, 2006 at 02:33:53PM +0200, Juergen Holm wrote:
>> On Sat, 20 May 2006, Luca Berra wrote:
>> 
>> > > Starting up RAID devices: mdadm: error opening /dev/md2: No such file 
>> > > or directoty
>> > > mdadm:   error opening /dev/md4: No such file or directory
>> > > mdadm:   error openlng /dev/md3: No such file or directory
>> > > mdadm:   error openlng /dev/md0: No such file or directory
>> > This looks like a known issue with mdadm and udev
>> > try addind "auto=yes" to each ARRAY line in mdadm.conf
>> 
>> With auto=yes in mdadm.conf my /dev/md? where found/created, and all
>> starts up as usaual!
>> Thanks for the tip!
>> 
>> 
>> > > 
>> > > 18mdk boots fine! I absolutly don't know what's going on!
>> > 
>> > i am quite surprised it works with -18mdk, it should have shown the same
>> > issue.
>> 
>> I tested a system with with softraid only for /home, run into the
>> problem and solved this with auto=yes also.
>
> i would like to clarify more,
> i still don't believe the first example you posted above could ever have
> worked with -18mdk (it does not work on my system)

Belive it or not, it is working!
Note, the / is on md1 in my first case.

> in the second case, it is possible that in case /home was md0 and root
> was md1 it worked with -18mdk
>
>> There IS definitly a change in the new kernel which prevents the creating
>> of the /dev/md? files.
>
> this is not 100% correct
> with -18mdk /dev/md0 is registered when md is loaded
> md != 0 are never registered at module loading
> with -21mdk no /dev/md* devices are registered at module loading
> -21mdk behaviour is the correct one (we should not register non-existent
> devices)

Agree. I didn't know this fact.
Curious: the mdadm.conf of initrd of 21mdk has no auto=yes, but anyway..

>> This ist really a showstopper for all systems  with softraid
>> upgrading to 21mdk, because auto=yes ist NOT the default during a 2006
>> installation!
> The issue with udev not creating md device files is well known.
> auto=yes is the default with 2006.0 drakx (check /usr/lib/libDrakX/raid.pm)
> i do not believe your arrays were created by 2006.0 drakx or 2006.0
> installer.

Ok my fault, you are right. The system was installed with 10.2 (I
believe) and upgraded with urpmi. Not very seldom.


>> I think you should make an announce of this Bug on the sec announce
>> list, to help other people not to run into the same problem.
> The difficult thing would be find the correct wording to describe this
> issue. 
> In any case, discussion on the md development list is gearing to making
> auto=yes the default, since too many people are getting bit by udev.

Somethine like this:
"users of softraid should ensure, that every ARRAY line in
mdadm.conf contains
 			auto=yes

before installing 21mdk. This is because of a change in registering  devices"


Luca, I can believe that it's  not easy to take so many different
situatons/configurations into account.
Thanks for the good work!


mfg,jh

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