linux-kernel - [PATCH] mac80211_hwsim: fixed use-after-free bug in hwsim_exit

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Date:   Wed, 7 Mar 2018 18:11:07 +0100
From:   Benjamin Beichler <benjamin.beichler@...-rostock.de>
To:     <johannes@...solutions.net>
CC:     <linux-wireless@...r.kernel.org>, <kvalo@...eaurora.org>,
        <syzbot+70ce058e01259de7bb1d@...kaller.appspotmail.com>,
        <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <syzkaller-bugs@...glegroups.com>,
        Benjamin Beichler <benjamin.beichler@...-rostock.de>
Subject: [PATCH] mac80211_hwsim: fixed 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@...kaller.appspotmail.com
Signed-off-by: Benjamin Beichler <benjamin.beichler@...-rostock.de>
---
 drivers/net/wireless/mac80211_hwsim.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 7b6c3640a94f..93a7ae34653e 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);
 
-- 
2.16.2