net: cdc_eem: fix tx fixup skb leak

Linyu Yuan · davem330 · commit c3b26fdf1b32 · 2021-06-17T11:30:25.000-07:00
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. Fixes: 9f722c0 ("usbnet: CDC EEM support (v5)") Signed-off-by: Linyu Yuan <linyyuan@codeaurora.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git 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:

Original file line number	Diff line number	Diff line change
`@@ -123,10 +123,10 @@ static struct sk_buff eem_tx_fixup(struct usbnet dev, struct sk_buff *skb,`
`123`	`123`	`}`
`124`	`124`
`125`	`125`	`skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);`
	`126`	`+ dev_kfree_skb_any(skb);`
`126`	`127`	`if (!skb2)`
`127`	`128`	`return NULL;`
`128`	`129`
`129`		`- dev_kfree_skb_any(skb);`
`130`	`130`	`skb = skb2;`
`131`	`131`
`132`	`132`	`done:`