linux-kernel - Re: hunt for 2.6.37 dm-crypt+ext4 corruption? (was: Re: dm-crypt barrier support is effective)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1291751698-sup-9297@think>
Date:	Tue, 07 Dec 2010 15:02:01 -0500
From:	Chris Mason <chris.mason@...cle.com>
To:	Jon Nelson <jnelson@...poni.net>
Cc:	Mike Snitzer <snitzer@...hat.com>, Matt <jackdachef@...il.com>,
	Milan Broz <mbroz@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	linux-btrfs <linux-btrfs@...r.kernel.org>,
	dm-devel <dm-devel@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	htd <htd@...cy-poultry.org>, htejun <htejun@...il.com>,
	linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: hunt for 2.6.37 dm-crypt+ext4 corruption? (was: Re: dm-crypt barrier support is effective)

Excerpts from Jon Nelson's message of 2010-12-07 14:34:40 -0500:
> On Tue, Dec 7, 2010 at 12:52 PM, Chris Mason <chris.mason@...cle.com> wrote:
> >> postgresql errors. Typically, header corruption but from the limited
> >> visibility I've had into this via strace, what I see is zeroed pages
> >> where there shouldn't be.
> >
> > This sounds a lot like a bug higher up than dm-crypt.  Zeros tend to
> > come from some piece of code explicitly filling a page with zeros, and
> > that often happens in the corner cases for O_DIRECT and a few other
> > places in the filesystem.
> >
> > Have you tried triggering this with a regular block device?
> 
> I just tried the whole set of tests, but with /dev/sdb directly (as
> ext4) without any crypt-y bits.
> It takes more iterations but out of 6 tests I had one failure: same
> type of thing, 'invalid page header in block ....'.
> 
> I can't guarantee that it is a full-page of zeroes, just what I saw
> from the (limited) stracing I did.

Fantastic. Now for our usual suspects:

1) Is postgres using O_DIRECT?  If yes, please turn it off
2) Is postgres allocating sparse files?  If yes, please have it fully
allocate the file instead.
3) Is postgres using preallocation (fallocate)?  If yes, please have it
fully allocate the file instead

-chris
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/