SCN wrapping

#11

On Jan 24, 9:46*am, Mark D Powell <Mark.Powe... (AT) hp (DOT) com> wrote:

Quote:

On Jan 20, 12:03*pm, joel garry <joel-ga... (AT) home (DOT) com> wrote:

On Jan 20, 12:39*am, mhoys <matthias.h... (AT) gmail (DOT) com> wrote:

On Jan 20, 1:09*am, joel garry <joel-ga... (AT) home (DOT) com> wrote:

On Jan 19, 12:11*pm, "Matthias Hoys" <a... (AT) spam (DOT) com> wrote:

"Mladen Gogala" <gogala.REMOVETHISmla... (AT) google (DOT) com> wrote in message

news:jf9kek$gk8$1 (AT) solani (DOT) org...

It appears that Oracle 11G has a rather serious bug: it wraps SCN numbers
around, when doing begin/end backup type of backup:

http://tinyurl.com/6wbker6

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http://mgogala.freehosta.com

I wonder if it's only 11g that's affected by the bug or also any older
versions? I don't remember reading anything about this in the last PSU patch
notes for 10g... And yes, there are still people using prehistoric
technology like 10g! ;-)

Matthias Hoys

Note the link I posted used 9i. *And we have another Wartiki-wannabe:http://blogs.oracle.com/UPGRADE/entr...e_flaw_reveale....

Mladen, see Bug 12371955 - Hot Backup can cause increased SCN growth
rate leading to ORA-600 [2252] errors [ID 12371955.8]
I think there is confusion because that was in 11.2.0.3, but is also
available as a patch 12371955 for earlier versions. *They don't seem
to put the old patches in the new listing you posted.

jg
--
@home.com is bogus.http://www.informationweek.com/news/...rity/232500111

Thanks, that MOS article helped to clear up the confusion a bit :-)
Looks like the bug was already fixed in the 11.2.0.3 server patch set..

And this is what they say about pre-11g versions:

*"This fix is *NOT* required in any release prior to 11g.
*For 11g onwards this fix is already included in various Patch Set
*Updates and bundles as listed above."

*getting even more confused*

Matthias Hoys

As I understand it, there are several issues, working together. *The
SCN being propagated among distributed databases appears to have been
around a long time, but never really had a problem because of the
large scale of the variable. *The bug that congealed the problem seems
to be the begin database backup which would elevate the SCN too fast.
That would only really be a problem for a large system with many links
and much usage of bcp style backups, where people would backup whole
dbs with a snapshot, rather than tablespaces, and the SCN jumps
propagating would multiply the problem. *Since it could happen, but
usually doesn't, they distribute a script to say red, amber or green
light, so most people get warm and fuzzy green lights.

But now that we know that, it is a simple matter to poison a system by
hacking the controlfiles of an obscure database, then propagate with a
mere access over a link. *You don't need the unpatched backup to have
the problem happen, someone can make it happen. *It may just be a
matter of time until it gets to the script-kiddie point (I haven't
looked yet this morning).

jg
--
@home.com is bogus.http://www.wired.com/wiredenterprise...racle-hp/-Hide quoted text -

- Show quoted text -

This bug is not nearly as risky as the InfoWorld article made out. *On
its own it is not likely to occur. *As far as a DOS attach goes if you
have proper control of your network and do not allow remote non-
controlled databases to link into yours then you can wait the time it
takes to upgrade/patch to a protected version in the normal course of
business.

You can implement monitoring of your SCN number and spit out an alert
or other form of warning message to identify an attach taking place.

IMHO -- Mark D Powell --

Ah, I missed the bit about ora-600 on the victim db if you went over a
reasonable SCN. Going through Bug 11767824: HIGH SCN VALUES / ORA-600
[2252] ERRORS while trying to understand what Jonathan said in some
places helped me understand much more. That shows the issue was there
in 10, even if that was kind of solved (or at least known and
trackable) and then made worse with the backup bug in 11.

Still glad I hadn't gone to snapshots and 11g though, even if only
through the luck of the budget-deprived. I'm definitely on the lag
side of http://mwidlake.wordpress.com/2012/0...en-to-upgrade/

You, Billy and Jonathan have brought me over to the tempest in a
teapot view, thanks.

jg
--
@home.com is bogus.
http://online.wsj.com/article/BT-CO-...24-711190.html

#12

According to InfoWorld a partial patch is in the January 2010 CPU. The magazine has issued an update which includes mention of another potential means of the issue being raised. The actual bug related to manual hot backups is apparently limited to two releases per the article, which also contains a link to an article on what and how Oracle uses the SCN number.

http://www.infoworld.com/d/security/...rmation-184775

HTH -- Mark D Powell --

#13

On Wed, 25 Jan 2012 07:56:29 -0800, Mark D Powell wrote:

Quote:

According to InfoWorld a partial patch is in the January 2010 CPU. The
magazine has issued an update which includes mention of another
potential means of the issue being raised. The actual bug related to
manual hot backups is apparently limited to two releases per the
article, which also contains a link to an article on what and how Oracle
uses the SCN number.

http://www.infoworld.com/d/security/...fications-and-
more-information-184775

HTH -- Mark D Powell --

Thanks, Mark. Fascinating reading. Good thing is that Infoworld is fair
and balanced.

--
http://mgogala.byethost5.com

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SCN wrapping

comp.databases.oracle.server comp.databases.oracle.server

Re: SCN wrapping - 01-24-2012 , 04:58 PM

Re: SCN wrapping - 01-25-2012 , 09:56 AM

Re: SCN wrapping - 01-25-2012 , 10:46 AM