target/linux/generic/backport-4.9/023-4-sr9700-use-skb_cow_head-to-deal-with-cloned-skbs.patch

   1 From d532c1082f68176363ed766d09bf187616e282fe Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Wed, 19 Apr 2017 09:59:23 -0700
   4 Subject: [PATCH] sr9700: 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: c9b37458e956 ("USB2NET : SR9700 : One chip USB 1.1 USB2NET SR9700Device Driver Support")
  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/sr9700.c | 9 ++-------
  17  1 file changed, 2 insertions(+), 7 deletions(-)
  18
  19 --- a/drivers/net/usb/sr9700.c
  20 +++ b/drivers/net/usb/sr9700.c
  21 @@ -456,14 +456,9 @@ static struct sk_buff *sr9700_tx_fixup(s
  22
  23         len = skb->len;
  24
  25 -       if (skb_headroom(skb) < SR_TX_OVERHEAD) {
  26 -               struct sk_buff *skb2;
  27 -
  28 -               skb2 = skb_copy_expand(skb, SR_TX_OVERHEAD, 0, flags);
  29 +       if (skb_cow_head(skb, SR_TX_OVERHEAD)) {
  30                 dev_kfree_skb_any(skb);
  31 -               skb = skb2;
  32 -               if (!skb)
  33 -                       return NULL;
  34 +               return NULL;
  35         }
  36
  37         __skb_push(skb, SR_TX_OVERHEAD);