From: Al Viro <viro@zeniv.linux.org.uk>
To: Christian Brauner <brauner@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Reinette Chatre <reinette.chatre@intel.com>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Richard Weinberger <richard@nod.at>,
Vignesh Raghavendra <vigneshr@ti.com>,
Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
Tejun Heo <tj@kernel.org>,
Trond Myklebust <trond.myklebust@hammerspace.com>,
Anna Schumaker <anna@kernel.org>,
Kees Cook <keescook@chromium.org>,
Damien Le Moal <dlemoal@kernel.org>,
Naohiro Aota <naohiro.aota@wdc.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-nfs@vger.kernel.org, linux-hardening@vger.kernel.org,
cgroups@vger.kernel.org
Subject: Re: [PATCH 03/19] fs: release anon dev_t in deactivate_locked_super
Date: Tue, 17 Oct 2023 20:50:41 +0100 [thread overview]
Message-ID: <20231017195041.GQ800259@ZenIV> (raw)
In-Reply-To: <20231010-zulagen-bisschen-9657746c1fc0@brauner>
On Tue, Oct 10, 2023 at 10:44:09AM +0200, Christian Brauner wrote:
> > list removal should happen after generic_shutdown_super(). Sure, you
> > want the superblock to serve as bdev holder, which leads to fun
> > with -EBUSY if mount comes while umount still hadn't closed the
> > device. I suspect that it would make a lot more sense to
> > introduce an intermediate state - "held, but will be released
> > in a short while". You already have something similar, but
> > only for the entire disk ->bd_claiming stuff.
> >
> > Add a new primitive (will_release_bdev()), so that attempts to
> > claim the sucker will wait until it gets released instead of
> > failing with -EBUSY. And do *that* before generic_shutdown_super()
> > when unmounting something that is block-based. Allows to bring
> > the list removal back where it used to be, no UAF at all...
>
> This is essentially equivalent to what is done right now. Only that this
> would then happen in the block layer. I'm not sure it would buy us that
> much. In all likelyhood we just get a range of other issues to fix.
The difference is, we separate the "close the block device" (which
can't be done until we stopped generating any IO on it, obviously)
from "tell anyone who wants to claim the sucker that we are going
to release it and they just need to wait". That can be done before
generic_shutdown_super(), or from it (e.g. from ->put_super()),
untangling the ordering mess.
next prev parent reply other threads:[~2023-10-17 19:51 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-13 11:09 split up ->kill_sb Christoph Hellwig
2023-09-13 11:09 ` [PATCH 01/19] fs: reflow deactivate_locked_super Christoph Hellwig
2023-09-13 16:35 ` Christian Brauner
2023-09-26 9:24 ` Christoph Hellwig
2023-09-13 11:09 ` [PATCH 02/19] fs: make ->kill_sb optional Christoph Hellwig
2023-09-13 11:09 ` [PATCH 03/19] fs: release anon dev_t in deactivate_locked_super Christoph Hellwig
2023-09-13 23:27 ` Al Viro
2023-09-14 2:37 ` Al Viro
2023-09-14 5:38 ` Al Viro
2023-09-14 7:56 ` Christian Brauner
2023-09-26 9:31 ` Christoph Hellwig
2023-09-14 14:02 ` Christian Brauner
2023-09-14 16:58 ` Al Viro
2023-09-14 19:23 ` Al Viro
2023-09-15 7:40 ` Christian Brauner
2023-09-15 9:44 ` Christian Brauner
2023-09-15 14:12 ` Christian Brauner
2023-09-15 14:28 ` Al Viro
2023-09-15 14:33 ` Al Viro
2023-09-15 14:40 ` Christian Brauner
2023-09-26 9:41 ` Christoph Hellwig
2023-09-26 9:38 ` Christoph Hellwig
2023-09-26 21:25 ` Al Viro
2023-09-27 22:29 ` Al Viro
2023-10-02 6:46 ` Christoph Hellwig
2023-10-09 21:57 ` Al Viro
2023-10-10 8:44 ` Christian Brauner
2023-10-17 19:50 ` Al Viro [this message]
2023-09-13 11:09 ` [PATCH 04/19] NFS: remove the s_dev field from struct nfs_server Christoph Hellwig
2023-09-13 11:09 ` [PATCH 05/19] fs: assign an anon dev_t in common code Christoph Hellwig
2023-09-14 0:34 ` Al Viro
2023-09-13 11:10 ` [PATCH 06/19] qibfs: use simple_release_fs Christoph Hellwig
2023-09-18 11:41 ` Leon Romanovsky
2023-09-13 11:10 ` [PATCH 07/19] hypfs: use d_genocide to kill fs entries Christoph Hellwig
2023-09-13 11:10 ` [PATCH 08/19] pstore: shrink the pstore_sb_lock critical section in pstore_kill_sb Christoph Hellwig
2023-09-13 22:07 ` Kees Cook
2023-09-13 11:10 ` [PATCH 09/19] zonefs: remove duplicate cleanup in zonefs_fill_super Christoph Hellwig
2023-09-14 0:33 ` Damien Le Moal
2023-09-14 0:49 ` Al Viro
2023-09-13 11:10 ` [PATCH 10/19] USB: gadget/legacy: remove sb_mutex Christoph Hellwig
2023-09-13 16:10 ` Alan Stern
2023-09-26 9:24 ` Christoph Hellwig
2023-09-14 10:22 ` Sergey Shtylyov
2023-09-13 11:10 ` [PATCH 11/19] fs: add new shutdown_sb and free_sb methods Christoph Hellwig
2023-09-14 2:07 ` Al Viro
2023-09-13 11:10 ` [PATCH 12/19] fs: convert kill_litter_super to litter_shutdown_sb Christoph Hellwig
2023-09-13 22:07 ` Kees Cook
2023-09-13 11:10 ` [PATCH 13/19] fs: convert kill_block_super to block_free_sb Christoph Hellwig
2023-09-14 2:29 ` Al Viro
2023-09-13 11:10 ` [PATCH 14/19] jffs2: convert to ->shutdown_sb and ->free_sb Christoph Hellwig
2023-09-13 11:10 ` [PATCH 15/19] kernfs: split ->kill_sb Christoph Hellwig
2023-09-18 15:24 ` Michal Koutný
2023-09-13 11:10 ` [PATCH 16/19] x86/resctrl: release rdtgroup_mutex and the CPU hotplug lock in rdt_shutdown_sb Christoph Hellwig
2023-09-13 11:10 ` [PATCH 17/19] NFS: move nfs_kill_super to fs_context.c Christoph Hellwig
2023-09-13 11:10 ` [PATCH 18/19] fs: simple ->shutdown_sb and ->free_sb conversions Christoph Hellwig
2023-09-13 11:10 ` [PATCH 19/19] fs: remove ->kill_sb Christoph Hellwig
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