staging: wfx: fix potential dead lock between join and scan

The device disallows to start a scan request between hif_join() and
hif_set_bss_params(). The driver is not protected against that. The
worst case happens when association is aborted and hif_set_bss_params()
never happens.

mac80211 would never ask for scan during the association process. So,
this patch just aborts the association in progress when scan is
requested.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200515083325.378539-14-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/scan.c

@@ -88,6 +88,11 @@ void wfx_hw_scan_work(struct work_struct *work)
 
 	mutex_lock(&wvif->wdev->conf_mutex);
 	mutex_lock(&wvif->scan_lock);
+	if (wvif->join_in_progress) {
+		dev_info(wvif->wdev->dev, "%s: abort in-progress REQ_JOIN",
+			 __func__);
+		wfx_reset(wvif);
+	}
 	update_probe_tmpl(wvif, &hw_req->req);
 	chan_cur = 0;
 	do {

drivers/staging/wfx/sta.c

@@ -353,6 +353,7 @@ void wfx_reset(struct wfx_vif *wvif)
 	if (wvif_count(wvif->wdev) <= 1)
 		hif_set_block_ack_policy(wvif, 0xFF, 0xFF);
 	wfx_tx_unlock(wvif->wdev);
+	wvif->join_in_progress = false;
 	wvif->bss_not_support_ps_poll = false;
 	cancel_delayed_work_sync(&wvif->beacon_loss_work);
 }
@@ -390,6 +391,7 @@ static void wfx_do_join(struct wfx_vif *wvif)
 	wfx_set_mfp(wvif, bss);
 	cfg80211_put_bss(wvif->wdev->hw->wiphy, bss);
 
+	wvif->join_in_progress = true;
 	ret = hif_join(wvif, conf, wvif->channel, ssid, ssidlen);
 	if (ret) {
 		ieee80211_connection_loss(wvif->vif);
@@ -485,6 +487,7 @@ void wfx_stop_ap(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
 static void wfx_join_finalize(struct wfx_vif *wvif,
 			      struct ieee80211_bss_conf *info)
 {
+	wvif->join_in_progress = false;
 	hif_set_association_mode(wvif, info);
 	hif_keep_alive_period(wvif, 0);
 	// beacon_loss_count is defined to 7 in net/mac80211/mlme.c. Let's use

drivers/staging/wfx/wfx.h

@@ -69,6 +69,8 @@ struct wfx_vif {
 	u32			link_id_map;
 
 	bool			after_dtim_tx_allowed;
+	bool			join_in_progress;
+
 	struct delayed_work	beacon_loss_work;
 
 	struct tx_policy_cache	tx_policy_cache;