netdev - [PATCH net] qmi_wwan: Clone the skb when in pass-through mode

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Message-Id: <20210614141849.3587683-1-kristian.evensen@gmail.com>
Date:   Mon, 14 Jun 2021 16:18:49 +0200
From:   Kristian Evensen <kristian.evensen@...il.com>
To:     bjorn@...k.no, netdev@...r.kernel.org, subashab@...eaurora.org
Cc:     Kristian Evensen <kristian.evensen@...il.com>
Subject: [PATCH net] qmi_wwan: Clone the skb when in pass-through mode

The skb that we pass to the rmnet driver is owned by usbnet and is freed
soon after the rx_fixup() callback is called (in usbnet_bh()).  There is
no guarantee that rmnet is done handling the skb before it is freed. We
should clone the skb before we call netif_rx() to prevent use-after-free
and misc. kernel oops.

Fixes: 59e139cf0b32 ("net: qmi_wwan: Add pass through mode")

Signed-off-by: Kristian Evensen <kristian.evensen@...il.com>
---
 drivers/net/usb/qmi_wwan.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
index db8d3a4f2678..5ac307eb0bfd 100644
--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -620,6 +620,10 @@ static int qmi_wwan_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 		return qmimux_rx_fixup(dev, skb);
 
 	if (info->flags & QMI_WWAN_FLAG_PASS_THROUGH) {
+		skb = skb_clone(skb, GFP_ATOMIC);
+		if (!skb)
+			return 0;
+
 		skb->protocol = htons(ETH_P_MAP);
 		return (netif_rx(skb) == NET_RX_SUCCESS);
 	}
-- 
2.25.1