USB: serial: kl5kusb105: fix line-state error handling

The current implementation failed to detect short transfers when
attempting to read the line state, and also, to make things worse,
logged the content of the uninitialised heap transfer buffer.

Fixes: abf492e ("USB: kl5kusb105: fix DMA buffers on stack")
Fixes: 1da177e ("Linux-2.6.12-rc2")
Cc: stable <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>

Author: jhovold

drivers/usb/serial/kl5kusb105.c

@@ -192,10 +192,11 @@ static int klsi_105_get_line_state(struct usb_serial_port *port,
 			     status_buf, KLSI_STATUSBUF_LEN,
 			     10000
 			     );
-	if (rc < 0)
-		dev_err(&port->dev, "Reading line status failed (error = %d)\n",
-			rc);
-	else {
+	if (rc != KLSI_STATUSBUF_LEN) {
+		dev_err(&port->dev, "reading line status failed: %d\n", rc);
+		if (rc >= 0)
+			rc = -EIO;
+	} else {
 		status = get_unaligned_le16(status_buf);
 
 		dev_info(&port->serial->dev->dev, "read status %x %x\n",