linux-kernel - Re: [PATCH] Bluetooth: virtio

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: <20211125154314-mutt-send-email-mst@kernel.org>
Date:   Thu, 25 Nov 2021 15:44:54 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Marcel Holtmann <marcel@...tmann.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-bluetooth@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH] Bluetooth: virtio_bt: fix device removal

On Thu, Nov 25, 2021 at 09:02:01PM +0100, Marcel Holtmann wrote:
> Hi Michael,
> 
> > Device removal is clearly out of virtio spec: it attempts to remove
> > unused buffers from a VQ before invoking device reset. To fix, make
> > open/close NOPs and do all cleanup/setup in probe/remove.
> 
> so the virtbt_{open,close} as NOP is not really what a driver is suppose
> to be doing. These are transport enable/disable callbacks from the BT
> Core towards the driver. It maps to a device being enabled/disabled by
> something like bluetoothd for example. So if disabled, I expect that no
> resources/queues are in use.
> 
> Maybe I misunderstand the virtio spec in that regard, but I would like
> to keep this fundamental concept of a Bluetooth driver. It does work
> with all other transports like USB, SDIO, UART etc.
> 
> > The cost here is a single skb wasted on an unused bt device - which
> > seems modest.
> 
> There should be no buffer used if the device is powered off. We also don’t
> have any USB URBs in-flight if the transport is not active.
> 
> > NB: with this fix in place driver still suffers from a race condition if
> > an interrupt triggers while device is being reset. Work on a fix for
> > that issue is in progress.
> 
> In the virtbt_close() callback we should deactivate all interrupts.
> 
> Regards
> 
> Marcel

If you want to do that then device has to be reset on close,
and fully reinitialized on open.
Can you work on a patch like that?
Given I don't have the device such a rework is probably more
than I can undertake.

-- 
MST