Commit ed3320ce authored Oct 20, 2020 by Oliver Hartkopp Committed by Marc Kleine-Budde Nov 03, 2020

can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames



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@wanadoo.fr>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/r/20201020064443.80164-1-socketcan@hartkopp.net


Fixes: cf5046b3 ("can: dev: let can_get_echo_skb() return dlc of CAN frame")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

parent 2283f79b

drivers/net/can/dev.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -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;

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