| From 7b12c8189a3dc50638e7d53714c88007268d47ef Mon Sep 17 00:00:00 2001 |
| From: Manfred Schlaegl <manfred.schlaegl@ginzinger.com> |
| Date: Wed, 19 Dec 2018 19:39:58 +0100 |
| Subject: can: dev: __can_get_echo_skb(): fix bogous check for non-existing skb by removing it |
| |
| From: Manfred Schlaegl <manfred.schlaegl@ginzinger.com> |
| |
| 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@ginzinger.com> |
| Fixes: 7da11ba5c506 ("can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb") |
| Cc: linux-stable <stable@vger.kernel.org> |
| Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| 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; |
| } |
| |
| /* |