target/linux/generic/pending-4.4/030-5-lan78xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch

   1 From d4ca73591916b760478d2b04334d5dcadc028e9c Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Wed, 19 Apr 2017 09:59:24 -0700
   4 Subject: [PATCH] lan78xx: use skb_cow_head() to deal with cloned skbs
   5
   6 We need to ensure there is enough headroom to push extra header,
   7 but we also need to check if we are allowed to change headers.
   8
   9 skb_cow_head() is the proper helper to deal with this.
  10
  11 Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
  12 Signed-off-by: Eric Dumazet <edumazet@google.com>
  13 Cc: James Hughes <james.hughes@raspberrypi.org>
  14 Cc: Woojung Huh <woojung.huh@microchip.com>
  15 Signed-off-by: David S. Miller <davem@davemloft.net>
  16 ---
  17  drivers/net/usb/lan78xx.c | 9 ++-------
  18  1 file changed, 2 insertions(+), 7 deletions(-)
  19
  20 --- a/drivers/net/usb/lan78xx.c
  21 +++ b/drivers/net/usb/lan78xx.c
  22 @@ -2050,14 +2050,9 @@ static struct sk_buff *lan78xx_tx_prep(s
  23  {
  24         u32 tx_cmd_a, tx_cmd_b;
  25
  26 -       if (skb_headroom(skb) < TX_OVERHEAD) {
  27 -               struct sk_buff *skb2;
  28 -
  29 -               skb2 = skb_copy_expand(skb, TX_OVERHEAD, 0, flags);
  30 +       if (skb_cow_head(skb, TX_OVERHEAD)) {
  31                 dev_kfree_skb_any(skb);
  32 -               skb = skb2;
  33 -               if (!skb)
  34 -                       return NULL;
  35 +               return NULL;
  36         }
  37
  38         if (lan78xx_linearize(skb) < 0)