[PATCH v2] rtw88: check for validity before using a pointer

-----Original Message-----
From: Muhammad Usama Anjum <redacted>
Sent: Friday, December 24, 2021 3:36 PM
To: Yan-Hsuan Chuang <redacted>; Kalle Valo <kvalo@kernel.org>; David S. Miller
[off-list ref]; Jakub Kicinski [off-list ref]; Bernie Huang [off-list ref]; Pkshih
[off-list ref]; open list:REALTEK WIRELESS DRIVER (rtw88) [off-list ref]; open
list:NETWORKING DRIVERS [off-list ref]; open list [off-list ref]
Cc: usama.anjum@collabora.com; kernel@collabora.com
Subject: [PATCH v2] rtw88: check for validity before using a pointer

ieee80211_probereq_get() can return NULL. Pointer skb should be checked
for validty before use. If it is not valid, list of skbs needs to be
freed to not memory leak.

Fixes: 10d162b2ed39 ("rtw88: 8822c: add ieee80211_ops::hw_scan")
Signed-off-by: Muhammad Usama Anjum <redacted>

---
v2:
Free the list in case of error
---
 drivers/net/wireless/realtek/rtw88/fw.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 2f7c036f9022..7e1fab7afb69 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c

@@ -1857,7 +1857,7 @@ 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;
+	struct sk_buff *skb, *tmp;
 	u8 num = req->n_ssids, i;

 	skb_queue_head_init(&list);

@@ -1866,11 +1866,19 @@ static int rtw_hw_scan_update_probe_req(struct rtw_dev *rtwdev,
 					     req->ssids[i].ssid,
 					     req->ssids[i].ssid_len,
 					     req->ie_len);
+		if (!skb)
+			goto out;
 		rtw_append_probe_req_ie(rtwdev, skb, &list, rtwvif);
 		kfree_skb(skb);
 	}

 	return _rtw_hw_scan_update_probe_req(rtwdev, num, &list);
+
+out:
+	skb_queue_walk_safe(&list, skb, tmp)

+		kfree_skb(skb);
+
+	return -ENOMEM;
 }

 static int rtw_add_chan_info(struct rtw_dev *rtwdev, struct rtw_chan_info *info,
--