[PATCH 1/3] ieee802154: Restore initial state on failed device_rename() in cfg802154_switch_netns()

[Ivan Abramov <i.abramov@mt-integration.ru>]

Currently, the return value of device_rename() is not acted upon.

To avoid an inconsistent state in case of failure, roll back the changes
made before the device_rename() call.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 66e5c2672cd1 ("ieee802154: add netns support")
Signed-off-by: Ivan Abramov <i.abramov@mt-integration.ru>
---
 net/ieee802154/core.c | 45 ++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 20 deletions(-)

diff --git a/net/ieee802154/core.c b/net/ieee802154/core.c
index 88adb04e4072..ddde594513a0 100644
--- a/net/ieee802154/core.c
+++ b/net/ieee802154/core.c
@@ -233,31 +233,36 @@ int cfg802154_switch_netns(struct cfg802154_registered_device *rdev,
 		wpan_dev->netdev->netns_local = true;
 	}
 
-	if (err) {
-		/* failed -- clean up to old netns */
-		net = wpan_phy_net(&rdev->wpan_phy);
-
-		list_for_each_entry_continue_reverse(wpan_dev,
-						     &rdev->wpan_dev_list,
-						     list) {
-			if (!wpan_dev->netdev)
-				continue;
-			wpan_dev->netdev->netns_local = false;
-			err = dev_change_net_namespace(wpan_dev->netdev, net,
-						       "wpan%d");
-			WARN_ON(err);
-			wpan_dev->netdev->netns_local = true;
-		}
-
-		return err;
-	}
-
-	wpan_phy_net_set(&rdev->wpan_phy, net);
+	if (err)
+		goto errout;
 
 	err = device_rename(&rdev->wpan_phy.dev, dev_name(&rdev->wpan_phy.dev));
 	WARN_ON(err);
 
+	if (err)
+		goto errout;
+
+	wpan_phy_net_set(&rdev->wpan_phy, net);
+
 	return 0;
+
+errout:
+	/* failed -- clean up to old netns */
+	net = wpan_phy_net(&rdev->wpan_phy);
+
+	list_for_each_entry_continue_reverse(wpan_dev,
+					     &rdev->wpan_dev_list,
+					     list) {
+		if (!wpan_dev->netdev)
+			continue;
+		wpan_dev->netdev->netns_local = false;
+		err = dev_change_net_namespace(wpan_dev->netdev, net,
+					       "wpan%d");
+		WARN_ON(err);
+		wpan_dev->netdev->netns_local = true;
+	}
+
+	return err;
 }
 
 void cfg802154_dev_free(struct cfg802154_registered_device *rdev)
-- 
2.39.5