FAILED: patch "[PATCH] mac80211_hwsim: fix use-after-free bug in hwsim_exit_net" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Benjamin Beichler <[email protected]>
Date: Wed, 7 Mar 2018 18:11:07 +0100
Subject: [PATCH] mac80211_hwsim: fix use-after-free bug in hwsim_exit_net

When destroying a net namespace, all hwsim interfaces, which are not created in default namespace are deleted. But the async deletion of the interfaces could last longer than the actual destruction of the namespace, which results to an use after free bug. Therefore use synchronous deletion in this case.

index 930ddef91093..d9527c7b50d4 100644
@@ -3528,8 +3528,12 @@ static void __net_exit hwsim_exit_net(struct net *net)
 		list_del(&data->list);
 		rhashtable_remove_fast(&hwsim_radios_rht, &data->rht,
 				       hwsim_rht_params);
-		INIT_WORK(&data->destroy_work, destroy_radio);
-		queue_work(hwsim_wq, &data->destroy_work);
+		hwsim_radios_generation++;
+		spin_unlock_bh(&hwsim_radio_lock);
+		mac80211_hwsim_del_radio(data,
+					 wiphy_name(data->hw->wiphy),
+					 NULL);
+		spin_lock_bh(&hwsim_radio_lock);
 	}
 	spin_unlock_bh(&hwsim_radio_lock);