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

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Message-ID: <YcV4Qkc9PrrmkOim@debian-BULLSEYE-live-builder-AMD64>
Date:   Fri, 24 Dec 2021 12:35:30 +0500
From:   Muhammad Usama Anjum <usama.anjum@...labora.com>
To:     Yan-Hsuan Chuang <tony0620emma@...il.com>,
        Kalle Valo <kvalo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Po-Hao Huang <phhuang@...ltek.com>,
        Ping-Ke Shih <pkshih@...ltek.com>,
        "open list:REALTEK WIRELESS DRIVER (rtw88)" 
        <linux-wireless@...r.kernel.org>,
        "open list:NETWORKING DRIVERS" <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Cc:     usama.anjum@...labora.com, kernel@...labora.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 <usama.anjum@...labora.com>

---
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,
-- 
2.30.2