netdev - Re: Sending undersized ARP packets with VXLAN L3 interface

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Date:	Wed, 27 Aug 2014 10:28:56 -0700
From:	Cong Wang <cwang@...pensource.com>
To:	Martin Rusko <martin.rusko@...il.com>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: Sending undersized ARP packets with VXLAN L3 interface

On Wed, Aug 27, 2014 at 10:06 AM, Martin Rusko <martin.rusko@...il.com> wrote:
>
> I'm wondering, where is the proper place to fix this. Should
> arp_create() function allocate skb big enough to produce ethernet
> frame with at least minimum size? Or is it somewhere in NIC drivers
> where small packets are padded with zeros?

Drivers do that, for example e1000:

        /* On PCI/PCI-X HW, if packet size is less than ETH_ZLEN,
         * packets may get corrupted during padding by HW.
         * To WA this issue, pad all small packets manually.
         */
        if (skb->len < ETH_ZLEN) {
                if (skb_pad(skb, ETH_ZLEN - skb->len))
                        return NETDEV_TX_OK;
                skb->len = ETH_ZLEN;
                skb_set_tail_pointer(skb, ETH_ZLEN);
        }
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