4.20-stable review patch. If anyone has any objections, please let me know.
------------------
From: Manfred Schlaegl <manfred.schlaegl@xxxxxxxxxxxxx>
commit 7b12c8189a3dc50638e7d53714c88007268d47ef upstream.
This patch revert commit 7da11ba5c506
("can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb")
After introduction of this change we encountered following new error
message on various i.MX plattforms (flexcan):
| flexcan 53fc8000.can can0: __can_get_echo_skb: BUG! Trying to echo non
| existing skb: can_priv::echo_skb[0]
The introduction of the message was a mistake because
priv->echo_skb[idx] = NULL is a perfectly valid in following case: If
CAN_RAW_LOOPBACK is disabled (setsockopt) in applications, the pkt_type
of the tx skb's given to can_put_echo_skb is set to PACKET_LOOPBACK. In
this case can_put_echo_skb will not set priv->echo_skb[idx]. It is
therefore kept NULL.
As additional argument for revert: The order of check and usage of idx
was changed. idx is used to access an array element before checking it's
boundaries.
Signed-off-by: Manfred Schlaegl <manfred.schlaegl@xxxxxxxxxxxxx>
Fixes: 7da11ba5c506 ("can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb")
Cc: linux-stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/can/dev.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -480,8 +480,6 @@ 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",
@@ -489,20 +487,21 @@ struct sk_buff *__can_get_echo_skb(struc
return NULL;
}
- if (!skb) {
- netdev_err(dev, "%s: BUG! Trying to echo non existing skb: can_priv::echo_skb[%u]\n",
- __func__, idx);
- 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;
- /* 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;
+ *len_ptr = len;
+ priv->echo_skb[idx] = NULL;
+
+ return skb;
+ }
- return skb;
+ return NULL;
}
/*
