linux-kernel - Re: [PATCH v2] xen-netfront: avoid crashing on resume after a failure in talk_to

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Message-Id: <20170511.213912.1393187351699676007.davem@davemloft.net>
Date:   Thu, 11 May 2017 21:39:12 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     vkuznets@...hat.com
Cc:     xen-devel@...ts.xenproject.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, boris.ostrovsky@...cle.com,
        jgross@...e.com
Subject: Re: [PATCH v2] xen-netfront: avoid crashing on resume after a
 failure in talk_to_netback()

From: Vitaly Kuznetsov <vkuznets@...hat.com>
Date: Thu, 11 May 2017 13:58:06 +0200

> Unavoidable crashes in netfront_resume() and netback_changed() after a
> previous fail in talk_to_netback() (e.g. when we fail to read MAC from
> xenstore) were discovered. The failure path in talk_to_netback() does
> unregister/free for netdev but we don't reset drvdata and we try accessing
> it after resume.
> 
> Fix the bug by removing the whole xen device completely with
> device_unregister(), this guarantees we won't have any calls into netfront
> after a failure.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
> Changes since v1: instead of cleaning drvdata and checking for it in
> netfront_resume() and netback_changed() remove the device completely with
> device_unregister() [David Miller]

This looks a lot better, applied, thanks!