linux-kernel - Re: [PATCH net-next v2 4/5] r8152: support skb_add_rx

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Date:   Fri, 16 Aug 2019 08:42:35 +0200
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Hayes Wang <hayeswang@...ltek.com>, netdev@...r.kernel.org
Cc:     nic_swsd@...ltek.com, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH net-next v2 4/5] r8152: support skb_add_rx_frag



On 8/13/19 5:42 AM, Hayes Wang wrote:
> Use skb_add_rx_frag() to reduce the memory copy for rx data.
> 
> Use a new list of rx_used to store the rx buffer which couldn't be
> reused yet.
> 
> Besides, the total number of rx buffer may be increased or decreased
> dynamically. And it is limited by RTL8152_MAX_RX_AGG.
> 
> Signed-off-by: Hayes Wang <hayeswang@...ltek.com>
>

...

>  			skb->protocol = eth_type_trans(skb, netdev);
>  			rtl_rx_vlan_tag(rx_desc, skb);
>  			if (work_done < budget) {
>  				napi_gro_receive(napi, skb);
>  				work_done++;
>  				stats->rx_packets++;
> -				stats->rx_bytes += pkt_len;
> +				stats->rx_bytes += skb->len;

use-after-free. skb is no longer in your hands after napi_gro_receive()