linux-kernel - Re: Mild filesystem corruption on ext4 (no journal)

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: <4A2937CC.7070503@redhat.com>
Date:	Fri, 05 Jun 2009 10:20:44 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
CC:	Aioanei Rares <krnl.list@...il.com>, linux-ext4@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Mild filesystem corruption on ext4 (no journal)

Alan Jenkins wrote:
> Aioanei Rares wrote:

>> I suspect, although I might be wrong, that this is not a kernel-related
>> problem.
> 
> "To try and rule out a faulty userspace program, I marked the file as 
> read-only (chmod a-w) and immutable (chattr +i).  After a reboot, the 
> file was still read-only and immutable, yet it still became corrupted."
> 
> Since the immutable bit is not respected, I tend to think it is a kernel 
> problem.  Unless the filesystem isn't getting unmounted/flushed properly 
> for some reason... but I thought the modern kernel had that covered.
> 
> I agree it is very suspicious this happens only after upgrading libc.  
> I'll see if I can find an individual change in libc locale-handling that 
> might trigger this.

Maybe you could try some things in your shutdown script, such as
explicitly fsyncing the file, or bmapping it with filefrag, or dropping
caches and rereading it... see what the state is just before the
shutdown compared to after the reboot.

-Eric
--
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/