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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+d7a3b15976bf7de2238a@syzkaller.appspotmail.com,
        Johannes Berg <johannes.berg@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 106/142] mac80211: pause TX while changing interface type
Date:   Tue,  2 Feb 2021 14:37:49 +0100
Message-Id: <20210202133002.082303954@linuxfoundation.org>
In-Reply-To: <20210202132957.692094111@linuxfoundation.org>
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From: Johannes Berg <johannes.berg@intel.com>

[ Upstream commit 054c9939b4800a91475d8d89905827bf9e1ad97a ]

syzbot reported a crash that happened when changing the interface
type around a lot, and while it might have been easy to fix just
the symptom there, a little deeper investigation found that really
the reason is that we allowed packets to be transmitted while in
the middle of changing the interface type.

Disallow TX by stopping the queues while changing the type.

Fixes: 34d4bc4d41d2 ("mac80211: support runtime interface type changes")
Reported-by: syzbot+d7a3b15976bf7de2238a@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20210122171115.b321f98f4d4f.I6997841933c17b093535c31d29355be3c0c39628@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/mac80211/ieee80211_i.h | 1 +
 net/mac80211/iface.c       | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 2a21226fb518a..d6913784be2bd 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1082,6 +1082,7 @@ enum queue_stop_reason {
 	IEEE80211_QUEUE_STOP_REASON_FLUSH,
 	IEEE80211_QUEUE_STOP_REASON_TDLS_TEARDOWN,
 	IEEE80211_QUEUE_STOP_REASON_RESERVE_TID,
+	IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE,
 
 	IEEE80211_QUEUE_STOP_REASONS,
 };
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 44154cc596cd4..f3c3557a9e4c4 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1654,6 +1654,10 @@ static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
 	if (ret)
 		return ret;
 
+	ieee80211_stop_vif_queues(local, sdata,
+				  IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE);
+	synchronize_net();
+
 	ieee80211_do_stop(sdata, false);
 
 	ieee80211_teardown_sdata(sdata);
@@ -1676,6 +1680,8 @@ static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
 	err = ieee80211_do_open(&sdata->wdev, false);
 	WARN(err, "type change: do_open returned %d", err);
 
+	ieee80211_wake_vif_queues(local, sdata,
+				  IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE);
 	return ret;
 }
 
-- 
2.27.0