linux-kernel - Re: ext3fs: umount+sync not enough to guarantee metadata-on-disk

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]

Date:	Thu, 07 Jun 2007 18:09:41 +0100
From:	"Stephen C. Tweedie" <sct@...hat.com>
To:	Mark Lord <lkml@....ca>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"Theodore Ts'o" <tytso@....edu>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Stephen Tweedie <sct@...hat.com>
Subject: Re: ext3fs: umount+sync not enough to guarantee metadata-on-disk

Hi,

On Thu, 2007-06-07 at 12:01 -0400, Mark Lord wrote:

> >>    mount /var/lib/mythtv -oremount,ro
> >>    sync
> >>    umount /var/lib/mythtv
> > 
> > Did this succeed?  If the application is still truncating that file, the
> > umount should have failed.
> 
> Actually, what I expect to happen is for the remount,ro
> to block  until the file deletion completes.  But it doesn't.

No -- all that the remount,ro sees is that there's a fd still open for
write.  It has no idea if or when that fd is going to get closed, so it
should fail.  Returning -EBUSY is the only thing it _can_ do: waiting
for the fs to be remountable might wait forever.

So the fs is still writable after that point.

--Stephen


-
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/