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Message-ID: <1528727372.2289.120.camel@codethink.co.uk>
Date: Mon, 11 Jun 2018 15:29:32 +0100
From: Ben Hutchings <ben.hutchings@...ethink.co.uk>
To: Ross Lagerwall <ross.lagerwall@...rix.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>
Cc: stable@...r.kernel.org,
Sasha Levin <alexander.levin@...rosoft.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4.4 059/268] xen-netfront: Fix race between device setup
and open
On Mon, 2018-05-28 at 12:00 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Ross Lagerwall <ross.lagerwall@...rix.com>
>
> [ Upstream commit f599c64fdf7d9c108e8717fb04bc41c680120da4 ]
[...]
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
[...]
> @@ -1839,6 +1824,7 @@ static int talk_to_netback(struct xenbus
> goto out;
This "goto out" is outside the locked section...
> }
>
> + rtnl_lock();
> if (info->queues)
> xennet_destroy_queues(info);
>
> @@ -1849,6 +1835,7 @@ static int talk_to_netback(struct xenbus
> info->queues = NULL;
> goto out;
> }
> + rtnl_unlock();
>
> /* Create shared ring, alloc event channel -- for each queue */
> for (i = 0; i < num_queues; ++i) {
> @@ -1945,8 +1932,10 @@ abort_transaction_no_dev_fatal:
> xenbus_transaction_end(xbt, 1);
> destroy_ring:
> xennet_disconnect_backend(info);
> + rtnl_lock();
> xennet_destroy_queues(info);
> out:
> + rtnl_unlock();
...so this will be an unmatched unlock.
You need to add another label below the rtnl_unlock().
Ben.
> device_unregister(&dev->dev);
> return err;
> }
[...]
--
Ben Hutchings, Software Developer Codethink Ltd
https://www.codethink.co.uk/ Dale House, 35 Dale Street
Manchester, M1 2HF, United Kingdom
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