Teach the net80211 stack to remove corresponding frames from ic_pwrsaveq

when a power-saving client decides to leave our hostap interface.

Prevents a "key unset for sw crypto" panic as we try to send a frame
to a node which is in COLLECT state with its WPA keys already cleared.

We were already clearing the queue which buffers power-saved frames for
the client node. This queue is stored within the node structure itself.
However, the interface has another global queue for frames which need to
be transmitted by the driver to a set of nodes during the next DTIM.
We missed removing frames for a departing node from this global queue.

While here, add missing node refcount adjustments as frames get purged.

Problem reported by Mikolaj Kucharski, who tested this fix for more
than a week with athn(4), with no further panics observed.

1 files changed, 37 insertions, 8 deletions

diff --git a/sys/net80211/ieee80211_node.c b/sys/net80211/ieee80211_node.c
index 752d139b056..98cac0edbe5 100644
--- a/sys/net80211/ieee80211_node.c
+++ b/sys/net80211/ieee80211_node.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ieee80211_node.c,v 1.189 2021/12/03 12:41:36 stsp Exp $	*/
+/*	$OpenBSD: ieee80211_node.c,v 1.190 2021/12/07 20:06:38 stsp Exp $	*/
 /*	$NetBSD: ieee80211_node.c,v 1.14 2004/05/09 09:18:47 dyoung Exp $	*/
 
 /*-
@@ -89,6 +89,8 @@ void ieee80211_node_join_11g(struct ieee80211com *, struct ieee80211_node *);
 void ieee80211_node_leave_ht(struct ieee80211com *, struct ieee80211_node *);
 void ieee80211_node_leave_rsn(struct ieee80211com *, struct ieee80211_node *);
 void ieee80211_node_leave_11g(struct ieee80211com *, struct ieee80211_node *);
+void ieee80211_node_leave_pwrsave(struct ieee80211com *,
+    struct ieee80211_node *);
 void ieee80211_inact_timeout(void *);
 void ieee80211_node_cache_timeout(void *);
 #endif
@@ -2866,6 +2868,39 @@ ieee80211_node_leave_11g(struct ieee80211com *ic, struct ieee80211_node *ni)
 	}
 }
 
+void
+ieee80211_node_leave_pwrsave(struct ieee80211com *ic,
+    struct ieee80211_node *ni)
+{
+	struct mbuf_queue keep = MBUF_QUEUE_INITIALIZER(IFQ_MAXLEN, IPL_NET);
+	struct mbuf *m;
+
+	if (ni->ni_pwrsave == IEEE80211_PS_DOZE)
+		ni->ni_pwrsave = IEEE80211_PS_AWAKE;
+
+	if (mq_len(&ni->ni_savedq) > 0) {
+		if (ic->ic_set_tim != NULL)
+			(*ic->ic_set_tim)(ic, ni->ni_associd, 0);
+	}
+	while ((m = mq_dequeue(&ni->ni_savedq)) != NULL) {
+		if (ni->ni_refcnt > 0)
+			ieee80211_node_decref(ni);
+		m_freem(m);
+	}
+
+	/* Purge frames queued for transmission during DTIM. */
+	while ((m = mq_dequeue(&ic->ic_pwrsaveq)) != NULL) {
+		if (m->m_pkthdr.ph_cookie == ni) {
+			if (ni->ni_refcnt > 0)
+				ieee80211_node_decref(ni);
+			m_freem(m);
+		} else
+			mq_enqueue(&keep, m);
+	}
+	while ((m = mq_dequeue(&keep)) != NULL)
+		mq_enqueue(&ic->ic_pwrsaveq, m);
+}
+
 /*
  * Handle bookkeeping for station deauthentication/disassociation
  * when operating as an ap.
@@ -2887,13 +2922,7 @@ ieee80211_node_leave(struct ieee80211com *ic, struct ieee80211_node *ni)
 		return;
 	}
 
-	if (ni->ni_pwrsave == IEEE80211_PS_DOZE)
-		ni->ni_pwrsave = IEEE80211_PS_AWAKE;
-
-	if (mq_purge(&ni->ni_savedq) > 0) {
-		if (ic->ic_set_tim != NULL)
-			(*ic->ic_set_tim)(ic, ni->ni_associd, 0);
-	}
+	ieee80211_node_leave_pwrsave(ic, ni);
 
 	if (ic->ic_flags & IEEE80211_F_RSNON)
 		ieee80211_node_leave_rsn(ic, ni);