releases/4.4.166/can-dev-__can_get_echo_skb-print-error-message-if-trying-to-echo-non-existing-skb.patch

   1 From 7da11ba5c5066dadc2e96835a6233d56d7b7764a Mon Sep 17 00:00:00 2001
   2 From: Marc Kleine-Budde <mkl@pengutronix.de>
   3 Date: Wed, 31 Oct 2018 14:15:13 +0100
   4 Subject: can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb
   5
   6 From: Marc Kleine-Budde <mkl@pengutronix.de>
   7
   8 commit 7da11ba5c5066dadc2e96835a6233d56d7b7764a upstream.
   9
  10 Prior to echoing a successfully transmitted CAN frame (by calling
  11 can_get_echo_skb()), CAN drivers have to put the CAN frame (by calling
  12 can_put_echo_skb() in the transmit function). These put and get function
  13 take an index as parameter, which is used to identify the CAN frame.
  14
  15 A driver calling can_get_echo_skb() with a index not pointing to a skb
  16 is a BUG, so add an appropriate error message.
  17
  18 Cc: linux-stable <stable@vger.kernel.org>
  19 Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  drivers/net/can/dev.c |   27 ++++++++++++++-------------
  24  1 file changed, 14 insertions(+), 13 deletions(-)
  25
  26 --- a/drivers/net/can/dev.c
  27 +++ b/drivers/net/can/dev.c
  28 @@ -426,6 +426,8 @@ EXPORT_SYMBOL_GPL(can_put_echo_skb);
  29  struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr)
  30  {
  31         struct can_priv *priv = netdev_priv(dev);
  32 +       struct sk_buff *skb = priv->echo_skb[idx];
  33 +       struct canfd_frame *cf;
  34
  35         if (idx >= priv->echo_skb_max) {
  36                 netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n",
  37 @@ -433,21 +435,20 @@ struct sk_buff *__can_get_echo_skb(struc
  38                 return NULL;
  39         }
  40
  41 -       if (priv->echo_skb[idx]) {
  42 -               /* Using "struct canfd_frame::len" for the frame
  43 -                * length is supported on both CAN and CANFD frames.
  44 -                */
  45 -               struct sk_buff *skb = priv->echo_skb[idx];
  46 -               struct canfd_frame *cf = (struct canfd_frame *)skb->data;
  47 -               u8 len = cf->len;
  48 -
  49 -               *len_ptr = len;
  50 -               priv->echo_skb[idx] = NULL;
  51 -
  52 -               return skb;
  53 +       if (!skb) {
  54 +               netdev_err(dev, "%s: BUG! Trying to echo non existing skb: can_priv::echo_skb[%u]\n",
  55 +                          __func__, idx);
  56 +               return NULL;
  57         }
  58
  59 -       return NULL;
  60 +       /* Using "struct canfd_frame::len" for the frame
  61 +        * length is supported on both CAN and CANFD frames.
  62 +        */
  63 +       cf = (struct canfd_frame *)skb->data;
  64 +       *len_ptr = cf->len;
  65 +       priv->echo_skb[idx] = NULL;
  66 +
  67 +       return skb;
  68  }
  69
  70  /*