[PATCH can 0/3] can: gs_usb: fix USB bulk in and out callbacks

[PATCH can 0/3] can: gs_usb: fix USB bulk in and out callbacks

[Marc Kleine-Budde]

The bulk-out callback gs_usb_xmit_callback() does not take care of the
cleanup of failed transfers of URBs. The 1st patch adds the missing
cleanup.

The bulk-in callback gs_usb_receive_bulk_callback() accesses the buffer of
the URB without checking how much data has actually been received. The last
2 patches fix this problem.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
Marc Kleine-Budde (3):
      can: gs_usb: gs_usb_xmit_callback(): fix handling of failed transmitted URBs
      can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing header
      can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data

 drivers/net/can/usb/gs_usb.c | 108 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 94 insertions(+), 14 deletions(-)
---
base-commit: 74d4432421a3e2669fbccc08c0f4fc2980bf0e39
change-id: 20251107-gs_usb-fix-usb-callbacks-5fa2955299c3

Best regards,
--  
Marc Kleine-Budde <mkl@pengutronix.de>

[PATCH can 1/3] can: gs_usb: gs_usb_xmit_callback(): fix handling of failed transmitted URBs

[Marc Kleine-Budde]

The driver lacks the cleanup of failed transfers of URBs. This reduces the
number of available URBs per error by 1. This leads to reduced performance
and ultimately to a complete stop of the transmission.

If the sending of a bulk URB fails do proper cleanup:
- increase netdev stats
- mark the echo_sbk as free
- free the driver's context and do accounting
- wake the send queue

Closes: https://github.com/candle-usb/candleLight_fw/issues/187
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/usb/gs_usb.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 69b8d6da651b..fa9bab8c89ae 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -750,8 +750,21 @@ static void gs_usb_xmit_callback(struct urb *urb)
 	struct gs_can *dev = txc->dev;
 	struct net_device *netdev = dev->netdev;
 
-	if (urb->status)
-		netdev_info(netdev, "usb xmit fail %u\n", txc->echo_id);
+	if (!urb->status)
+		return;
+
+	if (urb->status != -ESHUTDOWN && net_ratelimit())
+		netdev_info(netdev, "failed to xmit URB %u: %pe\n",
+			    txc->echo_id, ERR_PTR(urb->status));
+
+	netdev->stats.tx_dropped++;
+	netdev->stats.tx_errors++;
+
+	can_free_echo_skb(netdev, txc->echo_id, NULL);
+	gs_free_tx_context(txc);
+	atomic_dec(&dev->active_tx_urbs);
+
+	netif_wake_queue(netdev);
 }
 
 static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,

-- 
2.51.0

[PATCH can 2/3] can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing header

[Marc Kleine-Budde]

The driver expects to receive a struct gs_host_frame in
gs_usb_receive_bulk_callback().

Use struct_group to describe the header of the struct gs_host_frame and
check that we have at least received the header before accessing any
members of it.

To resubmit the URB, do not dereference the pointer chain
"dev->parent->hf_size_rx" but use "parent->hf_size_rx" instead. Since
"urb->context" contains "parent", it is always defined, while "dev" is not
defined if the URB it too short.

Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/usb/gs_usb.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index fa9bab8c89ae..51f8d694104d 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -262,13 +262,15 @@ struct canfd_quirk {
 } __packed;
 
 struct gs_host_frame {
-	u32 echo_id;
-	__le32 can_id;
+	struct_group(header,
+		u32 echo_id;
+		__le32 can_id;
 
-	u8 can_dlc;
-	u8 channel;
-	u8 flags;
-	u8 reserved;
+		u8 can_dlc;
+		u8 channel;
+		u8 flags;
+		u8 reserved;
+	);
 
 	union {
 		DECLARE_FLEX_ARRAY(struct classic_can, classic_can);
@@ -576,6 +578,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 	int rc;
 	struct net_device_stats *stats;
 	struct gs_host_frame *hf = urb->transfer_buffer;
+	unsigned int minimum_length;
 	struct gs_tx_context *txc;
 	struct can_frame *cf;
 	struct canfd_frame *cfd;
@@ -594,6 +597,15 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 		return;
 	}
 
+	minimum_length = sizeof(hf->header);
+	if (urb->actual_length < minimum_length) {
+		dev_err_ratelimited(&parent->udev->dev,
+				    "short read (actual_length=%u, minimum_length=%u)\n",
+				    urb->actual_length, minimum_length);
+
+		goto resubmit_urb;
+	}
+
 	/* device reports out of range channel id */
 	if (hf->channel >= parent->channel_cnt)
 		goto device_detach;
@@ -687,7 +699,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 resubmit_urb:
 	usb_fill_bulk_urb(urb, parent->udev,
 			  parent->pipe_in,
-			  hf, dev->parent->hf_size_rx,
+			  hf, parent->hf_size_rx,
 			  gs_usb_receive_bulk_callback, parent);
 
 	rc = usb_submit_urb(urb, GFP_ATOMIC);

-- 
2.51.0

[PATCH can 3/3] can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data

[Marc Kleine-Budde]

The URB received in gs_usb_receive_bulk_callback() contains a struct
gs_host_frame. The length of the data after the header depends on the
gs_host_frame hf::flags and the active device features (e.g. time
stamping).

Introduce a new function gs_usb_get_minimum_length() and check that we have
at least received the required amount of data before accessing it. Only
copy the data to that skb that has actually been received.

Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/usb/gs_usb.c | 65 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 60 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 51f8d694104d..8524d423b029 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -261,6 +261,11 @@ struct canfd_quirk {
 	u8 quirk;
 } __packed;
 
+/* struct gs_host_frame::echo_id == GS_HOST_FRAME_ECHO_ID_RX indicates
+ * a regular RX'ed CAN frame
+ */
+#define GS_HOST_FRAME_ECHO_ID_RX 0xffffffff
+
 struct gs_host_frame {
 	struct_group(header,
 		u32 echo_id;
@@ -570,6 +575,43 @@ gs_usb_get_echo_skb(struct gs_can *dev, struct sk_buff *skb,
 	return len;
 }
 
+static unsigned int
+gs_usb_get_minimum_length(const struct gs_can *dev, const struct gs_host_frame *hf,
+			  unsigned int *data_length_p)
+{
+	unsigned int minimum_length, data_length;
+
+	/* TX echo only uses the header */
+	if (hf->echo_id != GS_HOST_FRAME_ECHO_ID_RX) {
+		*data_length_p = 0;
+		return sizeof(hf->header);
+	}
+
+	if (hf->flags & GS_CAN_FLAG_FD) {
+		data_length = can_fd_dlc2len(hf->can_dlc);
+
+		if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
+			/* timestamp follows data field of max size */
+			minimum_length = struct_size(hf, canfd_ts, 1);
+		else
+			minimum_length = sizeof(hf->header) + data_length;
+	} else {
+		if (hf->can_id & cpu_to_le32(CAN_RTR_FLAG))
+			data_length = 0;
+		else
+			data_length = can_cc_dlc2len(hf->can_dlc);
+
+		if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
+			/* timestamp follows data field of max size */
+			minimum_length = struct_size(hf, classic_can_ts, 1);
+		else
+			minimum_length = sizeof(hf->header) + data_length;
+	}
+
+	*data_length_p = data_length;
+	return minimum_length;
+}
+
 static void gs_usb_receive_bulk_callback(struct urb *urb)
 {
 	struct gs_usb *parent = urb->context;
@@ -578,7 +620,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 	int rc;
 	struct net_device_stats *stats;
 	struct gs_host_frame *hf = urb->transfer_buffer;
-	unsigned int minimum_length;
+	unsigned int minimum_length, data_length;
 	struct gs_tx_context *txc;
 	struct can_frame *cf;
 	struct canfd_frame *cfd;
@@ -621,20 +663,33 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 	if (!netif_running(netdev))
 		goto resubmit_urb;
 
-	if (hf->echo_id == -1) { /* normal rx */
+	minimum_length = gs_usb_get_minimum_length(dev, hf, &data_length);
+	if (urb->actual_length < minimum_length) {
+		stats->rx_errors++;
+		stats->rx_length_errors++;
+
+		if (net_ratelimit())
+			netdev_err(netdev,
+				   "short read (actual_length=%u, minimum_length=%u)\n",
+				   urb->actual_length, minimum_length);
+
+		goto resubmit_urb;
+	}
+
+	if (hf->echo_id == GS_HOST_FRAME_ECHO_ID_RX) { /* normal rx */
 		if (hf->flags & GS_CAN_FLAG_FD) {
 			skb = alloc_canfd_skb(netdev, &cfd);
 			if (!skb)
 				return;
 
 			cfd->can_id = le32_to_cpu(hf->can_id);
-			cfd->len = can_fd_dlc2len(hf->can_dlc);
+			cfd->len = data_length;
 			if (hf->flags & GS_CAN_FLAG_BRS)
 				cfd->flags |= CANFD_BRS;
 			if (hf->flags & GS_CAN_FLAG_ESI)
 				cfd->flags |= CANFD_ESI;
 
-			memcpy(cfd->data, hf->canfd->data, cfd->len);
+			memcpy(cfd->data, hf->canfd->data, data_length);
 		} else {
 			skb = alloc_can_skb(netdev, &cf);
 			if (!skb)
@@ -643,7 +698,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 			cf->can_id = le32_to_cpu(hf->can_id);
 			can_frame_set_cc_len(cf, hf->can_dlc, dev->can.ctrlmode);
 
-			memcpy(cf->data, hf->classic_can->data, 8);
+			memcpy(cf->data, hf->classic_can->data, data_length);
 
 			/* ERROR frames tell us information about the controller */
 			if (le32_to_cpu(hf->can_id) & CAN_ERR_FLAG)

-- 
2.51.0

Re: [PATCH can 3/3] can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data

[Henrik Brix Andersen]

Hi,

> On 8 Nov 2025, at 10.01, Marc Kleine-Budde <mkl@pengutronix.de> wrote:
> 
> The URB received in gs_usb_receive_bulk_callback() contains a struct
> gs_host_frame. The length of the data after the header depends on the
> gs_host_frame hf::flags and the active device features (e.g. time
> stamping).
> 
> Introduce a new function gs_usb_get_minimum_length() and check that we have
> at least received the required amount of data before accessing it. Only
> copy the data to that skb that has actually been received.
> 
> Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> ---
> drivers/net/can/usb/gs_usb.c | 65 ++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 60 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
> index 51f8d694104d..8524d423b029 100644
> --- a/drivers/net/can/usb/gs_usb.c
> +++ b/drivers/net/can/usb/gs_usb.c
> @@ -261,6 +261,11 @@ struct canfd_quirk {
> u8 quirk;
> } __packed;
> 
> +/* struct gs_host_frame::echo_id == GS_HOST_FRAME_ECHO_ID_RX indicates
> + * a regular RX'ed CAN frame
> + */
> +#define GS_HOST_FRAME_ECHO_ID_RX 0xffffffff
> +
> struct gs_host_frame {
> struct_group(header,
> u32 echo_id;
> @@ -570,6 +575,43 @@ gs_usb_get_echo_skb(struct gs_can *dev, struct sk_buff *skb,
> return len;
> }
> 
> +static unsigned int
> +gs_usb_get_minimum_length(const struct gs_can *dev, const struct gs_host_frame *hf,
> +  unsigned int *data_length_p)
> +{
> + unsigned int minimum_length, data_length;
> +
> + /* TX echo only uses the header */
> + if (hf->echo_id != GS_HOST_FRAME_ECHO_ID_RX) {
> + *data_length_p = 0;
> + return sizeof(hf->header);
> + }

Is this correct? The embedded timestamp is also used in the gs_usb_get_echo_skb() function.

Regards,
Brix
-- 
Henrik Brix Andersen

Re: [PATCH can 3/3] can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data

[Marc Kleine-Budde]

[-- Attachment #1: Type: text/plain, Size: 846 bytes --]

On 11.11.2025 13:31:06, Henrik Brix Andersen wrote:
> > +static unsigned int
> > +gs_usb_get_minimum_length(const struct gs_can *dev, const struct gs_host_frame *hf,
> > +  unsigned int *data_length_p)
> > +{
> > + unsigned int minimum_length, data_length;
> > +
> > + /* TX echo only uses the header */
> > + if (hf->echo_id != GS_HOST_FRAME_ECHO_ID_RX) {
> > + *data_length_p = 0;
> > + return sizeof(hf->header);
> > + }
>
> Is this correct? The embedded timestamp is also used in the
> gs_usb_get_echo_skb() function.

Right, will update.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH can 0/3] can: gs_usb: fix USB bulk in and out callbacks

[Marc Kleine-Budde]

The bulk-out callback gs_usb_xmit_callback() does not take care of the
cleanup of failed transfers of URBs. The 1st patch adds the missing
cleanup.

The bulk-in callback gs_usb_receive_bulk_callback() accesses the buffer of
the URB without checking how much data has actually been received. The last
2 patches fix this problem.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
Changes in v2:
- patch 3: TX-echo length: take timestamps into account (thanks: Henrik)
- Link to v1: https://patch.msgid.link/20251108-gs_usb-fix-usb-callbacks-v1-0-8a2534a7ea05@pengutronix.de

---
Marc Kleine-Budde (3):
      can: gs_usb: gs_usb_xmit_callback(): fix handling of failed transmitted URBs
      can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing header
      can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data

 drivers/net/can/usb/gs_usb.c | 102 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 88 insertions(+), 14 deletions(-)
---
base-commit: 407a06507c2358554958e8164dc97176feddcafc
change-id: 20251107-gs_usb-fix-usb-callbacks-5fa2955299c3

Best regards,
--  
Marc Kleine-Budde <mkl@pengutronix.de>

[PATCH can 3/3] can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data

[Marc Kleine-Budde]

The URB received in gs_usb_receive_bulk_callback() contains a struct
gs_host_frame. The length of the data after the header depends on the
gs_host_frame hf::flags and the active device features (e.g. time
stamping).

Introduce a new function gs_usb_get_minimum_length() and check that we have
at least received the required amount of data before accessing it. Only
copy the data to that skb that has actually been received.

Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/usb/gs_usb.c | 59 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 54 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 51f8d694104d..ac84857b89e6 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -261,6 +261,11 @@ struct canfd_quirk {
 	u8 quirk;
 } __packed;
 
+/* struct gs_host_frame::echo_id == GS_HOST_FRAME_ECHO_ID_RX indicates
+ * a regular RX'ed CAN frame
+ */
+#define GS_HOST_FRAME_ECHO_ID_RX 0xffffffff
+
 struct gs_host_frame {
 	struct_group(header,
 		u32 echo_id;
@@ -570,6 +575,37 @@ gs_usb_get_echo_skb(struct gs_can *dev, struct sk_buff *skb,
 	return len;
 }
 
+static unsigned int
+gs_usb_get_minimum_length(const struct gs_can *dev, const struct gs_host_frame *hf,
+			  unsigned int *data_length_p)
+{
+	unsigned int minimum_length, data_length = 0;
+
+	if (hf->flags & GS_CAN_FLAG_FD) {
+		if (hf->echo_id == GS_HOST_FRAME_ECHO_ID_RX)
+			data_length = can_fd_dlc2len(hf->can_dlc);
+
+		if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
+			/* timestamp follows data field of max size */
+			minimum_length = struct_size(hf, canfd_ts, 1);
+		else
+			minimum_length = sizeof(hf->header) + data_length;
+	} else {
+		if (hf->echo_id == GS_HOST_FRAME_ECHO_ID_RX &&
+		    !(hf->can_id & cpu_to_le32(CAN_RTR_FLAG)))
+			data_length = can_cc_dlc2len(hf->can_dlc);
+
+		if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
+			/* timestamp follows data field of max size */
+			minimum_length = struct_size(hf, classic_can_ts, 1);
+		else
+			minimum_length = sizeof(hf->header) + data_length;
+	}
+
+	*data_length_p = data_length;
+	return minimum_length;
+}
+
 static void gs_usb_receive_bulk_callback(struct urb *urb)
 {
 	struct gs_usb *parent = urb->context;
@@ -578,7 +614,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 	int rc;
 	struct net_device_stats *stats;
 	struct gs_host_frame *hf = urb->transfer_buffer;
-	unsigned int minimum_length;
+	unsigned int minimum_length, data_length;
 	struct gs_tx_context *txc;
 	struct can_frame *cf;
 	struct canfd_frame *cfd;
@@ -621,20 +657,33 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 	if (!netif_running(netdev))
 		goto resubmit_urb;
 
-	if (hf->echo_id == -1) { /* normal rx */
+	minimum_length = gs_usb_get_minimum_length(dev, hf, &data_length);
+	if (urb->actual_length < minimum_length) {
+		stats->rx_errors++;
+		stats->rx_length_errors++;
+
+		if (net_ratelimit())
+			netdev_err(netdev,
+				   "short read (actual_length=%u, minimum_length=%u)\n",
+				   urb->actual_length, minimum_length);
+
+		goto resubmit_urb;
+	}
+
+	if (hf->echo_id == GS_HOST_FRAME_ECHO_ID_RX) { /* normal rx */
 		if (hf->flags & GS_CAN_FLAG_FD) {
 			skb = alloc_canfd_skb(netdev, &cfd);
 			if (!skb)
 				return;
 
 			cfd->can_id = le32_to_cpu(hf->can_id);
-			cfd->len = can_fd_dlc2len(hf->can_dlc);
+			cfd->len = data_length;
 			if (hf->flags & GS_CAN_FLAG_BRS)
 				cfd->flags |= CANFD_BRS;
 			if (hf->flags & GS_CAN_FLAG_ESI)
 				cfd->flags |= CANFD_ESI;
 
-			memcpy(cfd->data, hf->canfd->data, cfd->len);
+			memcpy(cfd->data, hf->canfd->data, data_length);
 		} else {
 			skb = alloc_can_skb(netdev, &cf);
 			if (!skb)
@@ -643,7 +692,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 			cf->can_id = le32_to_cpu(hf->can_id);
 			can_frame_set_cc_len(cf, hf->can_dlc, dev->can.ctrlmode);
 
-			memcpy(cf->data, hf->classic_can->data, 8);
+			memcpy(cf->data, hf->classic_can->data, data_length);
 
 			/* ERROR frames tell us information about the controller */
 			if (le32_to_cpu(hf->can_id) & CAN_ERR_FLAG)

-- 
2.51.0