[PATCH 4.9 045/120] USB: serial: kl5kusb105: fix line-state error handling

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@kernel.org>

commit 146cc8a17a3b4996f6805ee5c080e7101277c410 upstream.

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: abf492e7b3ae ("USB: kl5kusb105: fix DMA buffers on stack")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/serial/kl5kusb105.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/usb/serial/kl5kusb105.c
+++ b/drivers/usb/serial/kl5kusb105.c
@@ -192,10 +192,11 @@ static int klsi_105_get_line_state(struc
 			     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",