linux-kernel - Re: [announce] vfs-scale git tree update

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: <AANLkTikomwroDXYmtA1crJeEdcpo_T1-g=O1zhHie4sC@mail.gmail.com>
Date:	Tue, 11 Jan 2011 10:13:32 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	aelder@....com, Ian Kent <raven@...maw.net>
Cc:	Nick Piggin <npiggin@...nel.dk>, Al Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [announce] vfs-scale git tree update

[ Added Ian to cc - the BUG_ON() in d_set_d_op() triggers on autofs4,
see lkml thread for more details if you care ]

On Tue, Jan 11, 2011 at 9:57 AM, Alex Elder <aelder@....com> wrote:
>
> Looking at it quickly, I don't think that would matter for
> the case at hand.  I.e., that might be safer but it doesn't
> address the fact that these fields are getting initialized
> multiple times.

You're right - without looking closer or thinking about it any more, I
was thinking mkdir etc would create the new dentry, but it can easily
be a pre-existing negative one. So it's not like mkdir is always going
to be something new that can just be initialized.

So yeah, no race or anything like that required - just regular acceses.

That said, if we make sure that the d_op gets cleared (or the dentry
dropped) when something turns negative, and a negative lookup never
sets d_op, it should all basically work.

Can you figure out the exact sequence that causes this? Is it enough
to just mount something once?

                 Linus
--
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/