Commit 3583903f authored by Marc Kleine-Budde's avatar Marc Kleine-Budde Committed by Greg Kroah-Hartman

can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb

commit 7da11ba5c5066dadc2e96835a6233d56d7b7764a upstream.

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 <>
Signed-off-by: default avatarMarc Kleine-Budde <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent a48b4b9c
......@@ -426,6 +426,8 @@ 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",
......@@ -433,21 +435,20 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8
return NULL;
if (priv->echo_skb[idx]) {
if (!skb) {
netdev_err(dev, "%s: BUG! Trying to echo non existing skb: can_priv::echo_skb[%u]\n",
__func__, idx);
return NULL;
/* 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;
cf = (struct canfd_frame *)skb->data;
*len_ptr = cf->len;
priv->echo_skb[idx] = NULL;
return skb;
return NULL;
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