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From:   Felix Fietkau <nbd@nbd.name>
To:     linux-wireless@vger.kernel.org
Cc:     johannes@sipsolutions.net
Subject: [PATCH] mac80211: do not wake queues on a vif that is being stopped
Date:   Tue, 31 May 2022 21:08:24 +0200
Message-Id: <20220531190824.60019-1-nbd@nbd.name>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@nbd.name>
---
 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 41531478437c..15a73b7fdd75 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -377,7 +377,9 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, bool going_do
 	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 1e26b5235add..dad42d42aa84 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -301,6 +301,9 @@ 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;
 
-- 
2.36.1