This is a note to let you know that I've just added the patch titled mac80211_hwsim: drop pending frames on stop to the 5.12-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mac80211_hwsim-drop-pending-frames-on-stop.patch and it can be found in the queue-5.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 08d56e619dbfa4c98af169caa9acd43367a11826 Author: Johannes Berg <johannes.berg@xxxxxxxxx> Date: Mon May 17 17:04:31 2021 +0200 mac80211_hwsim: drop pending frames on stop [ Upstream commit bd18de517923903a177508fc8813f44e717b1c00 ] 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@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/20210517170429.b0f85ab0eda1.Ie42a6ec6b940c971f3441286aeaaae2fe368e29a@changeid Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c index fa7d4c20dc13..30b39cb4056a 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__); }