rtw88: fix memory overrun and memory leak during hw_scan

Previously we allocated less memory than actual required, overwrite
to the buffer causes the mm module to complaint and raise access
violation faults. Along with potential memory leaks when returned
early. Fix these by passing the correct size and proper deinit flow.

Fixes: 10d162b ("rtw88: 8822c: add ieee80211_ops::hw_scan")
Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220121070813.9656-4-pkshih@realtek.com

drivers/net/wireless/realtek/rtw88/fw.c

@@ -1784,9 +1784,9 @@ void rtw_fw_scan_notify(struct rtw_dev *rtwdev, bool start)
 	rtw_fw_send_h2c_command(rtwdev, h2c_pkt);
 }
 
-static void rtw_append_probe_req_ie(struct rtw_dev *rtwdev, struct sk_buff *skb,
-				    struct sk_buff_head *list,
-				    struct rtw_vif *rtwvif)
+static int rtw_append_probe_req_ie(struct rtw_dev *rtwdev, struct sk_buff *skb,
+				   struct sk_buff_head *list, u8 *bands,
+				   struct rtw_vif *rtwvif)
 {
 	struct ieee80211_scan_ies *ies = rtwvif->scan_ies;
 	struct rtw_chip_info *chip = rtwdev->chip;
@@ -1797,19 +1797,24 @@ static void rtw_append_probe_req_ie(struct rtw_dev *rtwdev, struct sk_buff *skb,
 		if (!(BIT(idx) & chip->band))
 			continue;
 		new = skb_copy(skb, GFP_KERNEL);
+		if (!new)
+			return -ENOMEM;
 		skb_put_data(new, ies->ies[idx], ies->len[idx]);
 		skb_put_data(new, ies->common_ies, ies->common_ie_len);
 		skb_queue_tail(list, new);
+		(*bands)++;
 	}
+
+	return 0;
 }
 
-static int _rtw_hw_scan_update_probe_req(struct rtw_dev *rtwdev, u8 num_ssids,
+static int _rtw_hw_scan_update_probe_req(struct rtw_dev *rtwdev, u8 num_probes,
 					 struct sk_buff_head *probe_req_list)
 {
 	struct rtw_chip_info *chip = rtwdev->chip;
 	struct sk_buff *skb, *tmp;
 	u8 page_offset = 1, *buf, page_size = chip->page_size;
-	u8 pages = page_offset + num_ssids * RTW_PROBE_PG_CNT;
+	u8 pages = page_offset + num_probes * RTW_PROBE_PG_CNT;
 	u16 pg_addr = rtwdev->fifo.rsvd_h2c_info_addr, loc;
 	u16 buf_offset = page_size * page_offset;
 	u8 tx_desc_sz = chip->tx_pkt_desc_sz;
@@ -1848,6 +1853,8 @@ static int _rtw_hw_scan_update_probe_req(struct rtw_dev *rtwdev, u8 num_ssids,
 	rtwdev->scan_info.probe_pg_size = page_offset;
 out:
 	kfree(buf);
+	skb_queue_walk(probe_req_list, skb)
+		kfree_skb(skb);
 
 	return ret;
 }
@@ -1858,27 +1865,34 @@ static int rtw_hw_scan_update_probe_req(struct rtw_dev *rtwdev,
 	struct cfg80211_scan_request *req = rtwvif->scan_req;
 	struct sk_buff_head list;
 	struct sk_buff *skb;
-	u8 num = req->n_ssids, i;
+	u8 num = req->n_ssids, i, bands = 0;
+	int ret;
 
 	skb_queue_head_init(&list);
 	for (i = 0; i < num; i++) {
 		skb = ieee80211_probereq_get(rtwdev->hw, rtwvif->mac_addr,
 					     req->ssids[i].ssid,
 					     req->ssids[i].ssid_len,
 					     req->ie_len);
-		if (!skb)
+		if (!skb) {
+			ret = -ENOMEM;
 			goto out;
-		rtw_append_probe_req_ie(rtwdev, skb, &list, rtwvif);
+		}
+		ret = rtw_append_probe_req_ie(rtwdev, skb, &list, &bands,
+					      rtwvif);
+		if (ret)
+			goto out;
+
 		kfree_skb(skb);
 	}
 
-	return _rtw_hw_scan_update_probe_req(rtwdev, num, &list);
+	return _rtw_hw_scan_update_probe_req(rtwdev, num * bands, &list);
 
 out:
 	skb_queue_walk(&list, skb)
 		kfree_skb(skb);
 
-	return -ENOMEM;
+	return ret;
 }
 
 static int rtw_add_chan_info(struct rtw_dev *rtwdev, struct rtw_chan_info *info,