[openwrt/openwrt] mac80211: add a bug fix for a rare crash

[LEDE Commits]

nbd pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/9a93b62f315ad4c9f021c414ed80ba337ab4a01e

commit 9a93b62f315ad4c9f021c414ed80ba337ab4a01e
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Sun Mar 27 00:05:49 2022 +0100

    mac80211: add a bug fix for a rare crash
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 ...-not-wake-queues-on-a-vif-that-is-being-s.patch | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)

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
index 0000000000..f0150ddef0
--- /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 at 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 at 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;
+