[PATCH v2 1/1] wifi: virt_wifi: don't transfer operstate before register

[Zihan Xi]

virt_wifi_newlink() calls netif_stacked_transfer_operstate() before
register_netdevice(). If the lower device is dormant, that queues the
new netdev on lweventlist while it is still uninitialized. If
registration fails after that, for example because of an invalid name
such as "bad/name", free_netdev() immediately frees the object. A
later linkwatch_fire_event() then use-after-frees the list entry.

Move the transfer to after netdev_upper_dev_link(), as macvlan and
ipvlan already do.

Fixes: c7cdba31ed8b ("mac80211-next: rtnetlink wifi simulation device")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Vega <vega@xxxxxxxxxx>
Assisted-by: LLM
Co-developed-by: Luxing Yin <root@xxxxxxxxxx>
Signed-off-by: Luxing Yin <root@xxxxxxxxxx>
Signed-off-by: Zihan Xi <zihanx@xxxxxxxxxx>
---
changes in v2:
  - Fix virt_wifi_newlink() instead of dropping events in
    linkwatch_fire_event().
  - Fixes: c7cdba31ed8b, the commit that added virt_wifi.
  - v1 Link:
    https://lore.kernel.org/all/cover.1788500348.git.zihanx@xxxxxxxxxx/

 drivers/net/wireless/virtual/virt_wifi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/virtual/virt_wifi.c b/drivers/net/wireless/virtual/virt_wifi.c
index b69a4650fba85..48afc2432f93a 100644
--- a/drivers/net/wireless/virtual/virt_wifi.c
+++ b/drivers/net/wireless/virtual/virt_wifi.c
@@ -558,7 +558,6 @@ static int virt_wifi_newlink(struct net_device *dev,
 	}
 
 	eth_hw_addr_inherit(dev, priv->lowerdev);
-	netif_stacked_transfer_operstate(priv->lowerdev, dev);
 
 	dev->ieee80211_ptr = kzalloc_obj(*dev->ieee80211_ptr);
 
@@ -584,6 +583,8 @@ static int virt_wifi_newlink(struct net_device *dev,
 		goto unregister_netdev;
 	}
 
+	netif_stacked_transfer_operstate(priv->lowerdev, dev);
+
 	dev->priv_destructor = virt_wifi_net_device_destructor;
 	priv->being_deleted = false;
 	priv->is_connected = false;
-- 
2.43.0