[PATCH] can: peak_usb: validate uCAN receive record lengths

[Pengpeng Hou]

pcan_usb_fd_decode_buf() walks uCAN records packed in one USB
receive buffer.

Require each record to contain the fixed header for its type, and verify
CAN payload bytes before copying them into the skb.

Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
 drivers/net/can/usb/peak_usb/pcan_usb_fd.c | 40 +++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
index eb4f5884ad73..45ae4611ae4c 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
@@ -566,6 +566,13 @@ static int pcan_usb_fd_decode_canmsg(struct pcan_usb_fd_if *usb_if,
 				     dev->can.ctrlmode);
 	}
 
+	if (!(rx_msg_flags & PUCAN_MSG_RTR) &&
+	    le16_to_cpu(rx_msg->size) - offsetof(struct pucan_rx_msg, d) <
+	    cfd->len) {
+		kfree_skb(skb);
+		return -EBADMSG;
+	}
+
 	cfd->can_id = le32_to_cpu(rm->can_id);
 
 	if (rx_msg_flags & PUCAN_MSG_EXT_ID)
@@ -714,6 +721,24 @@ static void pcan_usb_fd_decode_ts(struct pcan_usb_fd_if *usb_if,
 		peak_usb_set_ts_now(&usb_if->time_ref, le32_to_cpu(ts->ts_low));
 }
 
+static size_t pcan_usb_fd_rx_msg_min_size(u16 rx_msg_type)
+{
+	switch (rx_msg_type) {
+	case PUCAN_MSG_CAN_RX:
+		return offsetof(struct pucan_rx_msg, d);
+	case PCAN_UFD_MSG_CALIBRATION:
+		return sizeof(struct pcan_ufd_ts_msg);
+	case PUCAN_MSG_ERROR:
+		return sizeof(struct pucan_error_msg);
+	case PUCAN_MSG_STATUS:
+		return sizeof(struct pucan_status_msg);
+	case PCAN_UFD_MSG_OVERRUN:
+		return sizeof(struct pcan_ufd_ovr_msg);
+	default:
+		return sizeof(struct pucan_msg);
+	}
+}
+
 /* callback for bulk IN urb */
 static int pcan_usb_fd_decode_buf(struct peak_usb_device *dev, struct urb *urb)
 {
@@ -728,6 +753,12 @@ static int pcan_usb_fd_decode_buf(struct peak_usb_device *dev, struct urb *urb)
 	msg_end = urb->transfer_buffer + urb->actual_length;
 	for (; msg_ptr < msg_end;) {
 		u16 rx_msg_type, rx_msg_size;
+		size_t rx_msg_min_size;
+
+		if (msg_end - msg_ptr < sizeof(*rx_msg)) {
+			err = -EBADMSG;
+			break;
+		}
 
 		rx_msg = (struct pucan_msg *)msg_ptr;
 		if (!rx_msg->size) {
@@ -739,13 +770,20 @@ static int pcan_usb_fd_decode_buf(struct peak_usb_device *dev, struct urb *urb)
 		rx_msg_type = le16_to_cpu(rx_msg->type);
 
 		/* check if the record goes out of current packet */
-		if (msg_ptr + rx_msg_size > msg_end) {
+		if (rx_msg_size > msg_end - msg_ptr) {
 			netdev_err(netdev,
 				   "got frag rec: should inc usb rx buf sze\n");
 			err = -EBADMSG;
 			break;
 		}
 
+		rx_msg_min_size = pcan_usb_fd_rx_msg_min_size(rx_msg_type);
+		if (rx_msg_size < rx_msg_min_size) {
+			netdev_err(netdev, "got short rec\n");
+			err = -EBADMSG;
+			break;
+		}
+
 		switch (rx_msg_type) {
 		case PUCAN_MSG_CAN_RX:
 			err = pcan_usb_fd_decode_canmsg(usb_if, rx_msg);
-- 
2.43.0