Re: [PATCH v2] net: cdc_eem: fix tx fixup skb leak

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Jun 17, 2021 at 07:32:32AM +0800, Linyu Yuan wrote:
> 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: 9f722c0978b0 ("usbnet: CDC EEM support (v5)")
> Signed-off-by: Linyu Yuan <linyyuan@codeaurora.org>
> ---
> 
> v2: add Fixes tag
> 
>  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
> 

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>