FAILED: patch "[PATCH] mac80211_hwsim: fix use-after-free bug in hwsim_exit_net" failed to apply to 4.14-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.14-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 <stable@vger.kernel.org>.

thanks,

greg k-h

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

>From 8cfd36a0b53aeb4ec21d81eb79706697b84dfc3d Mon Sep 17 00:00:00 2001
From: Benjamin Beichler <benjamin.beichler@uni-rostock.de>
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.

Fixes: 100cb9ff40e0 ("mac80211_hwsim: Allow managing radios from non-initial namespaces")
Reported-by: syzbot+70ce058e01259de7bb1d@syzkaller.appspotmail.com
Signed-off-by: Benjamin Beichler <benjamin.beichler@uni-rostock.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 930ddef91093..d9527c7b50d4 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -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);