This is a note to let you know that I've just added the patch titled can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: can-dev-__can_get_echo_skb-fix-real-payload-length-r.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 4c924ae8369d487b38eb391be944312c993c31c5 Author: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Date: Tue Oct 20 08:44:43 2020 +0200 can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames [ Upstream commit ed3320cec279407a86bc4c72edc4a39eb49165ec ] 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> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index be532eb64baa2..1950b13f22dfc 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -493,9 +493,13 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 */ 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;