netdev - [PATCH] net: cdc_eem: fix tx fixup skb leak

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Date:   Wed, 16 Jun 2021 22:40:44 +0800
From:   Linyu Yuan <linyyuan@...eaurora.org>
To:     Oliver Neukum <oliver@...kum.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     linux-usb@...r.kernel.org, netdev@...r.kernel.org,
        Linyu Yuan <linyyuan@...eaurora.org>
Subject: [PATCH] net: cdc_eem: fix tx fixup skb leak

when usbnet transmit a skb, eem fixup it in eem_tx_fixup(),
if skb_copy_expand() failed, it return NULL,
usbnet_start_xmit() will have no chance to free original skb.

fix it by free orginal skb in eem_tx_fixup() first,
then check skb clone status, if failed, return NULL to usbnet.

Signed-off-by: Linyu Yuan <linyyuan@...eaurora.org>
---
 drivers/net/usb/cdc_eem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/usb/cdc_eem.c b/drivers/net/usb/cdc_eem.c
index 2e60bc1b9a6b..359ea0d10e59 100644
--- a/drivers/net/usb/cdc_eem.c
+++ b/drivers/net/usb/cdc_eem.c
@@ -123,10 +123,10 @@ static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
 	}
 
 	skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
+	dev_kfree_skb_any(skb);
 	if (!skb2)
 		return NULL;
 
-	dev_kfree_skb_any(skb);
 	skb = skb2;
 
 done:
-- 
2.25.1