From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: xen-devel@lists.xenproject.org
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>
Subject: [PATCH] xen-netfront: avoid crashing on resume after a failure in talk_to_netback()
Date: Thu, 4 May 2017 14:23:04 +0200 [thread overview]
Message-ID: <20170504122304.11735-1-vkuznets@redhat.com> (raw)
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 again after resume.
Reset drvdata in netback_changed() the same way we reset it in
netfront_probe() and check for NULL in both netfront_resume() and
netback_changed() to properly handle the situation.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
I apologize for sending this during the merge window, I'm not sure if this
needs to go through xen or netdev tree. I think the fix is simple enough
and it would make sense to squeeze it in 4.12 if possible. Thanks.
---
drivers/net/xen-netfront.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 6ffc482..92f746c 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1426,6 +1426,9 @@ static int netfront_resume(struct xenbus_device *dev)
{
struct netfront_info *info = dev_get_drvdata(&dev->dev);
+ if (!info)
+ return 0;
+
dev_dbg(&dev->dev, "%s\n", dev->nodename);
xennet_disconnect_backend(info);
@@ -1936,6 +1939,7 @@ static int talk_to_netback(struct xenbus_device *dev,
out:
unregister_netdev(info->netdev);
xennet_free_netdev(info->netdev);
+ dev_set_drvdata(&dev->dev, NULL);
return err;
}
@@ -1997,7 +2001,12 @@ static void netback_changed(struct xenbus_device *dev,
enum xenbus_state backend_state)
{
struct netfront_info *np = dev_get_drvdata(&dev->dev);
- struct net_device *netdev = np->netdev;
+ struct net_device *netdev;
+
+ if (!np)
+ return;
+
+ netdev = np->netdev;
dev_dbg(&dev->dev, "%s\n", xenbus_strstate(backend_state));
--
2.9.3
next reply other threads:[~2017-05-04 12:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-04 12:23 Vitaly Kuznetsov [this message]
2017-05-04 15:21 ` [PATCH] xen-netfront: avoid crashing on resume after a failure in talk_to_netback() David Miller
2017-05-05 14:40 ` Vitaly Kuznetsov
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