wifi: mac80211: disable softirqs for queued frame handling

As noticed by syzbot, calling ieee80211_handle_queued_frames()
(and actually handling frames there) requires softirqs to be
disabled, since we call into the RX code. Fix that in the case
of cleaning up frames left over during shutdown.

Fixes: 177c6ae972 ("wifi: mac80211: handle tasklet frames before stopping")
Reported-by: syzbot+1d516edf1e74469ba5d3@syzkaller.appspotmail.com
Link: https://patch.msgid.link/20240626091559.cd6f08105a6e.I74778610a5ff2cf8680964698131099d2960352a@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/main.c

@@ -423,6 +423,7 @@ u64 ieee80211_reset_erp_info(struct ieee80211_sub_if_data *sdata)
 	       BSS_CHANGED_ERP_SLOT;
 }
 
+/* context: requires softirqs disabled */
 void ieee80211_handle_queued_frames(struct ieee80211_local *local)
 {
 	struct sk_buff *skb;

net/mac80211/util.c

@@ -1567,7 +1567,9 @@ u32 ieee80211_sta_get_rates(struct ieee80211_sub_if_data *sdata,
 
 void ieee80211_stop_device(struct ieee80211_local *local)
 {
+	local_bh_disable();
 	ieee80211_handle_queued_frames(local);
+	local_bh_enable();
 
 	ieee80211_led_radio(local, false);
 	ieee80211_mod_tpt_led_trig(local, 0, IEEE80211_TPT_LEDTRIG_FL_RADIO);