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From:   Larry Finger <Larry.Finger@lwfinger.net>
To:     kvalo@codeaurora.org
Cc:     linux-wireless@vger.kernel.org, pkshih@realtek.com,
        Larry Finger <Larry.Finger@lwfinger.net>,
        Stable <stable@vger.kernel.org>
Subject: [PATCH] rtlwifi: rtl_pci: Fix problem of too small skb->len
Date:   Sat, 19 Oct 2019 14:02:22 -0500
Message-Id: <20191019190222.29681-1-Larry.Finger@lwfinger.net>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

In commit 8020919a9b99 ("mac80211: Properly handle SKB with radiotap
only"), buffers whose length is too short cause a WARN_ON(1) to be
executed. This change exposed a fault in rtlwifi drivers, which is fixed
by increasing the length of the affected buffer before it is sent to
mac80211.

Cc: Stable <stable@vger.kernel.org> # v5.0+
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
---

Kalle,

Please send to v5.4.

Larry
---

 drivers/net/wireless/realtek/rtlwifi/pci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtlwifi/pci.c b/drivers/net/wireless/realtek/rtlwifi/pci.c
index 6087ec7a90a6..bb5144b7c64f 100644
--- a/drivers/net/wireless/realtek/rtlwifi/pci.c
+++ b/drivers/net/wireless/realtek/rtlwifi/pci.c
@@ -692,7 +692,10 @@ static void _rtl_pci_rx_to_mac80211(struct ieee80211_hw *hw,
 		dev_kfree_skb_any(skb);
 	} else {
 		struct sk_buff *uskb = NULL;
+		int len = skb->len;
 
+		if (unlikely(len <= FCS_LEN))
+			len = FCS_LEN + 2;
 		uskb = dev_alloc_skb(skb->len + 128);
 		if (likely(uskb)) {
 			memcpy(IEEE80211_SKB_RXCB(uskb), &rx_status,
-- 
2.23.0