releases/4.9.255/mac80211-pause-tx-while-changing-interface-type.patch

From ec69d8d9dd5e348dbb9f8d9f9c1730056427b0ae Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Fri, 22 Jan 2021 17:11:16 +0100
Subject: mac80211: pause TX while changing interface type

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 0b0de3030e0dc..9c20c53f6729e 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1046,6 +1046,7 @@ 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 ad03331ee7855..7d43e0085cfc7 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1577,6 +1577,10 @@ 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);
@@ -1597,6 +1601,8 @@ 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