From: William Tu
> Sent: 05 October 2017 01:14
> Similarly to early patch for erspan_xmit(), the ARPHDR_ETHER device
> is the length of the whole ether packet. So skb->len should subtract
> the dev->hard_header_len.
>
> Fixes: 1a66a836da63 ("gre: add collect_md mode to ERSPAN tunnel")
> Signed-off-by: William Tu <u9012...@gmail.com>
> Cc: Xin Long <lucien....@gmail.com>
> ---
> net/ipv4/ip_gre.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
> index b279c325c7f6..10b21fe5b3a6 100644
> --- a/net/ipv4/ip_gre.c
> +++ b/net/ipv4/ip_gre.c
> @@ -579,7 +579,7 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct
> net_device *dev,
> if (gre_handle_offloads(skb, false))
> goto err_free_rt;
>
> - if (skb->len > dev->mtu) {
> + if (skb->len - dev->hard_header_len > dev->mtu) {
Can you guarantee that skb->len > dev_hard_header_len?
It is probably safer to check skb->len > dev->hard_header_len + dev->mtu
since that addition isn't going to overflow.
> pskb_trim(skb, dev->mtu);
> truncate = true;
Is that pskb_trim() now truncating to the correct size?
David
