From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> The can_get_echo_skb() function returns the number of received bytes to be used for netdev statistics. In the case of RTR frames we get a valid (potential non-zero) data length value which has to be passed for further operations. But on the wire RTR frames have no payload length. Therefore the value to be used in the statistics has to be zero for RTR frames. Reported-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20201020064443.80164-1-socketcan@xxxxxxxxxxxx Fixes: cf5046b309b3 ("can: dev: let can_get_echo_skb() return dlc of CAN frame") Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- drivers/net/can/dev.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 73cfcd7e9517..6dee4f8f2024 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -512,9 +512,13 @@ __can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr) */ struct sk_buff *skb = priv->echo_skb[idx]; struct canfd_frame *cf = (struct canfd_frame *)skb->data; - u8 len = cf->len; - *len_ptr = len; + /* get the real payload length for netdev statistics */ + if (cf->can_id & CAN_RTR_FLAG) + *len_ptr = 0; + else + *len_ptr = cf->len; + priv->echo_skb[idx] = NULL; return skb; -- 2.28.0
