From bd18de517923903a177508fc8813f44e717b1c00 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Mon, 17 May 2021 17:04:31 +0200
Subject: [PATCH] mac80211_hwsim: drop pending frames on stop
Git-commit: bd18de517923903a177508fc8813f44e717b1c00
Patch-mainline: v5.13-rc7
References: git-fixes

Syzbot reports that we may be able to get into a situation where
mac80211 has pending ACK frames on shutdown with hwsim. It appears
that the reason for this is that syzbot uses the wmediumd hooks to
intercept/injection frames, and may shut down hwsim, removing the
radio(s), while frames are pending in the air simulation.

Clean out the pending queue when the interface is stopped, after
this the frames can't be reported back to mac80211 properly anyway.

Reported-by: syzbot+a063bbf0b15737362592@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20210517170429.b0f85ab0eda1.Ie42a6ec6b940c971f3441286aeaaae2fe368e29a@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/mac80211_hwsim.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 51ce767eaf88..7a6fd46d0c6e 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -1693,8 +1693,13 @@ static int mac80211_hwsim_start(struct ieee80211_hw *hw)
 static void mac80211_hwsim_stop(struct ieee80211_hw *hw)
 {
 	struct mac80211_hwsim_data *data = hw->priv;
+
 	data->started = false;
 	hrtimer_cancel(&data->beacon_timer);
+
+	while (!skb_queue_empty(&data->pending))
+		ieee80211_free_txskb(hw, skb_dequeue(&data->pending));
+
 	wiphy_dbg(hw->wiphy, "%s\n", __func__);
 }
 
-- 
2.26.2