git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From 4c924ae8369d487b38eb391be944312c993c31c5 Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Tue, 20 Oct 2020 08:44:43 +0200
   4 Subject: can: dev: __can_get_echo_skb(): fix real payload length return value
   5  for RTR frames
   6
   7 From: Oliver Hartkopp <socketcan@hartkopp.net>
   8
   9 [ Upstream commit ed3320cec279407a86bc4c72edc4a39eb49165ec ]
  10
  11 The can_get_echo_skb() function returns the number of received bytes to
  12 be used for netdev statistics. In the case of RTR frames we get a valid
  13 (potential non-zero) data length value which has to be passed for further
  14 operations. But on the wire RTR frames have no payload length. Therefore
  15 the value to be used in the statistics has to be zero for RTR frames.
  16
  17 Reported-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
  18 Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
  19 Link: https://lore.kernel.org/r/20201020064443.80164-1-socketcan@hartkopp.net
  20 Fixes: cf5046b309b3 ("can: dev: let can_get_echo_skb() return dlc of CAN frame")
  21 Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
  22 Signed-off-by: Sasha Levin <sashal@kernel.org>
  23 ---
  24  drivers/net/can/dev.c | 8 ++++++--
  25  1 file changed, 6 insertions(+), 2 deletions(-)
  26
  27 diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
  28 index be532eb64baa2..1950b13f22dfc 100644
  29 --- a/drivers/net/can/dev.c
  30 +++ b/drivers/net/can/dev.c
  31 @@ -493,9 +493,13 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8
  32                  */
  33                 struct sk_buff *skb = priv->echo_skb[idx];
  34                 struct canfd_frame *cf = (struct canfd_frame *)skb->data;
  35 -               u8 len = cf->len;
  36
  37 -               *len_ptr = len;
  38 +               /* get the real payload length for netdev statistics */
  39 +               if (cf->can_id & CAN_RTR_FLAG)
  40 +                       *len_ptr = 0;
  41 +               else
  42 +                       *len_ptr = cf->len;
  43 +
  44                 priv->echo_skb[idx] = NULL;
  45
  46                 return skb;
  47 --
  48 2.27.0
  49