From a4310fa2f24687888ce80fdb0e88583561a23700 Mon Sep 17 00:00:00 2001 From: Marc Kleine-Budde Date: Wed, 31 Oct 2018 10:37:46 +0100 Subject: can: dev: can_get_echo_skb(): factor out non sending code to __can_get_echo_skb() This patch factors out all non sending parts of can_get_echo_skb() into a seperate function __can_get_echo_skb(), so that it can be re-used in an upcoming patch. Cc: linux-stable Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) (limited to 'drivers/net/can/dev.c') diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 49163570a63a..80530ab37b1e 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -477,14 +477,7 @@ void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, } EXPORT_SYMBOL_GPL(can_put_echo_skb); -/* - * Get the skb from the stack and loop it back locally - * - * The function is typically called when the TX done interrupt - * is handled in the device driver. The driver must protect - * access to priv->echo_skb, if necessary. - */ -unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx) +struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr) { struct can_priv *priv = netdev_priv(dev); @@ -495,13 +488,34 @@ unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx) struct can_frame *cf = (struct can_frame *)skb->data; u8 dlc = cf->can_dlc; - netif_rx(priv->echo_skb[idx]); + *len_ptr = dlc; priv->echo_skb[idx] = NULL; - return dlc; + return skb; } - return 0; + return NULL; +} + +/* + * Get the skb from the stack and loop it back locally + * + * The function is typically called when the TX done interrupt + * is handled in the device driver. The driver must protect + * access to priv->echo_skb, if necessary. + */ +unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx) +{ + struct sk_buff *skb; + u8 len; + + skb = __can_get_echo_skb(dev, idx, &len); + if (!skb) + return 0; + + netif_rx(skb); + + return len; } EXPORT_SYMBOL_GPL(can_get_echo_skb); -- cgit From 200f5c49f7a2cd694436bfc6cb0662b794c96736 Mon Sep 17 00:00:00 2001 From: Marc Kleine-Budde Date: Wed, 31 Oct 2018 11:08:21 +0100 Subject: can: dev: __can_get_echo_skb(): replace struct can_frame by canfd_frame to access frame length This patch replaces the use of "struct can_frame::can_dlc" by "struct canfd_frame::len" to access the frame's length. As it is ensured that both structures have a compatible memory layout for this member this is no functional change. Futher, this compatibility is documented in a comment. Cc: linux-stable Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'drivers/net/can/dev.c') diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 80530ab37b1e..46cc5fec4043 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -484,11 +484,14 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 BUG_ON(idx >= priv->echo_skb_max); 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 can_frame *cf = (struct can_frame *)skb->data; - u8 dlc = cf->can_dlc; + struct canfd_frame *cf = (struct canfd_frame *)skb->data; + u8 len = cf->len; - *len_ptr = dlc; + *len_ptr = len; priv->echo_skb[idx] = NULL; return skb; -- cgit From e7a6994d043a1e31d5b17706a22ce33d2a3e4cdc Mon Sep 17 00:00:00 2001 From: Marc Kleine-Budde Date: Wed, 31 Oct 2018 14:05:26 +0100 Subject: can: dev: __can_get_echo_skb(): Don't crash the kernel if can_priv::echo_skb is accessed out of bounds If the "struct can_priv::echo_skb" is accessed out of bounds would lead to a kernel crash. Better print a sensible warning message instead and try to recover. Cc: linux-stable Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'drivers/net/can/dev.c') diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 46cc5fec4043..c05e4d50d43d 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -481,7 +481,11 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 { struct can_priv *priv = netdev_priv(dev); - BUG_ON(idx >= priv->echo_skb_max); + 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", + __func__, idx, priv->echo_skb_max); + return NULL; + } if (priv->echo_skb[idx]) { /* Using "struct canfd_frame::len" for the frame -- cgit From 7da11ba5c5066dadc2e96835a6233d56d7b7764a Mon Sep 17 00:00:00 2001 From: Marc Kleine-Budde Date: Wed, 31 Oct 2018 14:15:13 +0100 Subject: can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb 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: Marc Kleine-Budde --- drivers/net/can/dev.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) (limited to 'drivers/net/can/dev.c') 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; } /* -- cgit