linux-kernel - Re: [git pull] vfs and fs fixes

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: <CA+55aFzTKt43-qm4se2ac24kEVQO=aH8sckh0e-Lf-wydnYHfg@mail.gmail.com>
Date:	Tue, 17 Apr 2012 09:33:06 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	Al Viro <viro@...iv.linux.org.uk>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [git pull] vfs and fs fixes

On Tue, Apr 17, 2012 at 9:22 AM, J. Bruce Fields <bfields@...ldses.org> wrote:
>
> Ugh, no, I think you're right:
>
>        rename A/a->A/b
>        rename B/b->B/b
>
> where A/a and B/a are the same file, and A/b and B/b are the same file,
> can result in the first rename holding the lock on A and a and waiting
> on b, and the second holding the lock on B and b and waiting on a.

In fact I don't think you need even that much. Just a simple

  touch a
  ln a b
  mv a b

looks like it should deadlock on itself, no? source and dest inodes
will be the same, so the mutex_lock() will just deadlock without even
any ABBA race.

(I didn't really check - maybe there is some reason that doesn't happen).

                  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/