netdev - RE: [PATCH] net: usb: ax88179_178a: fix packet alignment padding

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Date:   Wed, 17 Jun 2020 14:39:40 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Jeremy Kerr' <jk@...abs.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Allan Chou <allan@...x.com.tw>, Freddy Xin <freddy@...x.com.tw>,
        "Peter Fink" <pfink@...ist-es.de>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: [PATCH] net: usb: ax88179_178a: fix packet alignment padding

From: Jeremy Kerr
> Sent: 15 June 2020 03:55

While you are looking as this driver you might want to worry
about what it sets skp->truesize to.

> --- a/drivers/net/usb/ax88179_178a.c
> +++ b/drivers/net/usb/ax88179_178a.c
> @@ -1414,10 +1414,10 @@ static int ax88179_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
>  		}
> 
>  		if (pkt_cnt == 0) {
> -			/* Skip IP alignment psudo header */
> -			skb_pull(skb, 2);
>  			skb->len = pkt_len;
> -			skb_set_tail_pointer(skb, pkt_len);
> +			/* Skip IP alignment pseudo header */
> +			skb_pull(skb, 2);
> +			skb_set_tail_pointer(skb, skb->len);
>  			skb->truesize = pkt_len + sizeof(struct sk_buff);

IIRC the memory allocated to the packet is likely to be over 64k.

	David

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