Prior to echoing a successfully transmitted CAN frame (by calling can_get_echo_skb()), CAN drivers have to put the CAN frame (by calling can_put_echo_skb() in the transmit function). These put and get function take an index as parameter, which is used to identify the CAN frame.

A driver calling can_get_echo_skb() with a index not pointing to a skb is a BUG, so add an appropriate error message.

Cc: linux-stable stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- drivers/net/can/dev.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index c05e4d50d43d..3b3f88ffab53 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -480,6 +480,8 @@ EXPORT_SYMBOL_GPL(can_put_echo_skb); struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr) { struct can_priv *priv = netdev_priv(dev); + struct sk_buff *skb = priv->echo_skb[idx]; + struct canfd_frame *cf;

if (idx >= priv->echo_skb_max) { netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n", @@ -487,21 +489,20 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 return NULL; }

- if (priv->echo_skb[idx]) { - /* Using "struct canfd_frame::len" for the frame - * length is supported on both CAN and CANFD frames. - */ - struct sk_buff *skb = priv->echo_skb[idx]; - struct canfd_frame *cf = (struct canfd_frame *)skb->data; - u8 len = cf->len; - - *len_ptr = len; - priv->echo_skb[idx] = NULL; - - return skb; + if (!skb) { + netdev_err(dev, "%s: BUG! Trying to echo non existing skb: can_priv::echo_skb[%u]\n", + __func__, idx); + return NULL; }

- return NULL; + /* Using "struct canfd_frame::len" for the frame + * length is supported on both CAN and CANFD frames. + */ + cf = (struct canfd_frame *)skb->data; + *len_ptr = cf->len; + priv->echo_skb[idx] = NULL; + + return skb; }

/*