netdev - [PATCH AUTOSEL 5.4 06/16] wifi: mac80211: do not wake queues on a vif that is being stopped

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Date:   Tue, 19 Jul 2022 21:17:20 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Felix Fietkau <nbd@....name>,
        Toke Høiland-Jørgensen <toke@...nel.org>,
        Johannes Berg <johannes.berg@...el.com>,
        Sasha Levin <sashal@...nel.org>, johannes@...solutions.net,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 06/16] wifi: mac80211: do not wake queues on a vif that is being stopped

From: Felix Fietkau <nbd@....name>

[ Upstream commit f856373e2f31ffd340e47e2b00027bd4070f74b3 ]

When a vif is being removed and sdata->bss is cleared, __ieee80211_wake_txqs
can still be called on it, which crashes as soon as sdata->bss is being
dereferenced.
To fix this properly, check for SDATA_STATE_RUNNING before waking queues,
and take the fq lock when setting it (to ensure that __ieee80211_wake_txqs
observes the change when running on a different CPU)

Signed-off-by: Felix Fietkau <nbd@....name>
Acked-by: Toke Høiland-Jørgensen <toke@...nel.org>
Link: https://lore.kernel.org/r/20220531190824.60019-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mac80211/iface.c | 2 ++
 net/mac80211/util.c  | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index ddc001ad9055..48bda8aaa90a 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -803,7 +803,9 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 	bool cancel_scan;
 	struct cfg80211_nan_func *func;
 
+	spin_lock_bh(&local->fq.lock);
 	clear_bit(SDATA_STATE_RUNNING, &sdata->state);
+	spin_unlock_bh(&local->fq.lock);
 
 	cancel_scan = rcu_access_pointer(local->scan_sdata) == sdata;
 	if (cancel_scan)
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index c1c117fdf318..8ae0186091b6 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -250,6 +250,9 @@ static void __ieee80211_wake_txqs(struct ieee80211_sub_if_data *sdata, int ac)
 	local_bh_disable();
 	spin_lock(&fq->lock);
 
+	if (!test_bit(SDATA_STATE_RUNNING, &sdata->state))
+		goto out;
+
 	if (sdata->vif.type == NL80211_IFTYPE_AP)
 		ps = &sdata->bss->ps;
 
-- 
2.35.1