wifi: mac80211: handle tasklet frames before stopping

The code itself doesn't want to handle frames from the driver
if it's already stopped, but if the tasklet was queued before
and runs after the stop, then all bets are off. Flush queues
before actually stopping, RX should be off at this point since
all the interfaces are removed already, etc.

Reported-by: syzbot+8830db5d3593b5546d2e@syzkaller.appspotmail.com
Link: https://msgid.link/20240515135318.b05f11385c9a.I41c1b33a2e1814c3a7ef352cd7f2951b91785617@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -1845,6 +1845,8 @@ void ieee80211_link_info_change_notify(struct ieee80211_sub_if_data *sdata,
 void ieee80211_configure_filter(struct ieee80211_local *local);
 u64 ieee80211_reset_erp_info(struct ieee80211_sub_if_data *sdata);
 
+void ieee80211_handle_queued_frames(struct ieee80211_local *local);
+
 u64 ieee80211_mgmt_tx_cookie(struct ieee80211_local *local);
 int ieee80211_attach_ack_skb(struct ieee80211_local *local, struct sk_buff *skb,
 			     u64 *cookie, gfp_t gfp);

net/mac80211/main.c

@@ -423,9 +423,8 @@ u64 ieee80211_reset_erp_info(struct ieee80211_sub_if_data *sdata)
 	       BSS_CHANGED_ERP_SLOT;
 }
 
-static void ieee80211_tasklet_handler(struct tasklet_struct *t)
+void ieee80211_handle_queued_frames(struct ieee80211_local *local)
 {
-	struct ieee80211_local *local = from_tasklet(local, t, tasklet);
 	struct sk_buff *skb;
 
 	while ((skb = skb_dequeue(&local->skb_queue)) ||
@@ -450,6 +449,13 @@ static void ieee80211_tasklet_handler(struct tasklet_struct *t)
 	}
 }
 
+static void ieee80211_tasklet_handler(struct tasklet_struct *t)
+{
+	struct ieee80211_local *local = from_tasklet(local, t, tasklet);
+
+	ieee80211_handle_queued_frames(local);
+}
+
 static void ieee80211_restart_work(struct work_struct *work)
 {
 	struct ieee80211_local *local =

net/mac80211/util.c

@@ -1567,6 +1567,8 @@ u32 ieee80211_sta_get_rates(struct ieee80211_sub_if_data *sdata,
 
 void ieee80211_stop_device(struct ieee80211_local *local)
 {
+	ieee80211_handle_queued_frames(local);
+
 	ieee80211_led_radio(local, false);
 	ieee80211_mod_tpt_led_trig(local, 0, IEEE80211_TPT_LEDTRIG_FL_RADIO);