[PATCH v3] rtw88: check for validity before using a pointer

From: Muhammad Usama Anjum <usama.anjum@collabora.com>
To: Yan-Hsuan Chuang <tony0620emma@gmail.com>,
	Kalle Valo <kvalo@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Ping-Ke Shih <pkshih@realtek.com>,
	Po-Hao Huang <phhuang@realtek.com>,
	"open list:REALTEK WIRELESS DRIVER (rtw88)" 
	<linux-wireless@vger.kernel.org>,
	"open list:NETWORKING DRIVERS" <netdev@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>
Cc: usama.anjum@collabora.com, kernel@collabora.com
Subject: [PATCH v3] rtw88: check for validity before using a pointer
Date: Fri, 24 Dec 2021 13:54:46 +0500	[thread overview]
Message-ID: <YcWK1jxnd3vGdmCq@debian-BULLSEYE-live-builder-AMD64> (raw)

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.

Fixes: 10d162b2ed39 ("rtw88: 8822c: add ieee80211_ops::hw_scan")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>

---
v3:
Use skb_queue_walk instead of skb_queue_walk_safe
v2:
Free the list in case of error
---
 drivers/net/wireless/realtek/rtw88/fw.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 2f7c036f9022..b56dc43229d2 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -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(&list, skb)
+		kfree_skb(skb);
+
+	return -ENOMEM;
 }
 
 static int rtw_add_chan_info(struct rtw_dev *rtwdev, struct rtw_chan_info *info,
-- 
2.30.2

