target/linux/generic/patches-4.9/023-2-smsc75xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch

   1 From b7c6d2675899cfff0180412c63fc9cbd5bacdb4d Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Wed, 19 Apr 2017 09:59:21 -0700
   4 Subject: [PATCH] smsc75xx: 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: d0cad871703b ("smsc75xx: SMSC LAN75xx USB gigabit ethernet adapter driver")
  12 Signed-off-by: Eric Dumazet <edumazet@google.com>
  13 Cc: James Hughes <james.hughes@raspberrypi.org>
  14 Signed-off-by: David S. Miller <davem@davemloft.net>
  15 ---
  16  drivers/net/usb/smsc75xx.c | 8 ++------
  17  1 file changed, 2 insertions(+), 6 deletions(-)
  18
  19 --- a/drivers/net/usb/smsc75xx.c
  20 +++ b/drivers/net/usb/smsc75xx.c
  21 @@ -2205,13 +2205,9 @@ static struct sk_buff *smsc75xx_tx_fixup
  22  {
  23         u32 tx_cmd_a, tx_cmd_b;
  24
  25 -       if (skb_headroom(skb) < SMSC75XX_TX_OVERHEAD) {
  26 -               struct sk_buff *skb2 =
  27 -                       skb_copy_expand(skb, SMSC75XX_TX_OVERHEAD, 0, flags);
  28 +       if (skb_cow_head(skb, SMSC75XX_TX_OVERHEAD)) {
  29                 dev_kfree_skb_any(skb);
  30 -               skb = skb2;
  31 -               if (!skb)
  32 -                       return NULL;
  33 +               return NULL;
  34         }
  35
  36         tx_cmd_a = (u32)(skb->len & TX_CMD_A_LEN) | TX_CMD_A_FCS;