The wait and bulk receive paths walk variable-length commands from a
USB buffer. A nonzero command shorter than CMD_HEADER_LEN can still be
dispatched, and the wait path copies a matching command into a fixed
caller-owned struct kvaser_cmd using the device-provided length.

Reject nonzero commands that do not contain the fixed header or that
extend beyond the current USB buffer item. In the wait path, also reject
a matching command that exceeds the destination before copying it.

Fixes: 080f40a6fa28 ("can: kvaser_usb: Add support for Kvaser CAN/USB devices")
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
 drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
index df737cfc5ea0..a876c7819b81 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
@@ -691,13 +691,22 @@ static int kvaser_usb_leaf_wait_cmd(const struct kvaser_usb *dev, u8 id,
 				continue;
 			}
 
-			if (pos + tmp->len > actual_len) {
+			if (tmp->len < CMD_HEADER_LEN ||
+			    tmp->len > actual_len - pos) {
 				dev_err_ratelimited(&dev->intf->dev,
 						    "Format error\n");
 				break;
 			}
 
 			if (tmp->id == id) {
+				if (tmp->len > sizeof(*cmd)) {
+					dev_err_ratelimited(&dev->intf->dev,
+							    "Received command %u too large (%u)\n",
+							    tmp->id, tmp->len);
+					err = -EIO;
+					goto end;
+				}
+
 				memcpy(cmd, tmp, tmp->len);
 				goto end;
 			}
@@ -1737,7 +1746,7 @@ static void kvaser_usb_leaf_read_bulk_callback(struct kvaser_usb *dev,
 			continue;
 		}
 
-		if (pos + cmd->len > len) {
+		if (cmd->len < CMD_HEADER_LEN || cmd->len > len - pos) {
 			dev_err_ratelimited(&dev->intf->dev, "Format error\n");
 			break;
 		}
-- 
2.50.1 (Apple Git-155)