target/linux/generic/backport-4.9/023-6-ch9200-use-skb_cow_head-to-deal-with-cloned-skbs.patch

   1 From 6bc6895bdd6744e0136eaa4a11fbdb20a7db4e40 Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Wed, 19 Apr 2017 09:59:25 -0700
   4 Subject: [PATCH] ch9200: 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: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices")
  12 Signed-off-by: Eric Dumazet <edumazet@google.com>
  13 Cc: James Hughes <james.hughes@raspberrypi.org>
  14 Cc: Matthew Garrett <mjg59@srcf.ucam.org>
  15 Signed-off-by: David S. Miller <davem@davemloft.net>
  16 ---
  17  drivers/net/usb/ch9200.c | 9 ++-------
  18  1 file changed, 2 insertions(+), 7 deletions(-)
  19
  20 --- a/drivers/net/usb/ch9200.c
  21 +++ b/drivers/net/usb/ch9200.c
  22 @@ -254,14 +254,9 @@ static struct sk_buff *ch9200_tx_fixup(s
  23         tx_overhead = 0x40;
  24
  25         len = skb->len;
  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         __skb_push(skb, tx_overhead);