mac80211: add a bug fix for a rare crash

Signed-off-by: Felix Fietkau <nbd@nbd.name>
(cherry picked from commit 9a93b62f315ad4c9f021c414ed80ba337ab4a01e)

diff --git a/package/kernel/mac80211/patches/subsys/328-mac80211-do-not-wake-queues-on-a-vif-that-is-being-s.patch b/package/kernel/mac80211/patches/subsys/328-mac80211-do-not-wake-queues-on-a-vif-that-is-being-s.patch
new file mode 100644 (file)
index 0000000..f0150dd
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/328-mac80211-do-not-wake-queues-on-a-vif-that-is-being-s.patch
@@ -0,0 +1,38 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 26 Mar 2022 23:58:35 +0100
+Subject: [PATCH] mac80211: do not wake queues on a vif that is being stopped
+
+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>
+---
+
+--- a/net/mac80211/iface.c
++++ b/net/mac80211/iface.c
+@@ -377,7 +377,9 @@ static void ieee80211_do_stop(struct iee
+       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)
+--- a/net/mac80211/util.c
++++ b/net/mac80211/util.c
+@@ -301,6 +301,9 @@ static void __ieee80211_wake_txqs(struct
+       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;
+