[PATCH 3.12 104/123] USB: symbolserial: Correct transferred data size

[Jiri Slaby]

From: Philipp Hachtmann <hachti@xxxxxxxxx>

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

===============

commit 8ae25a355b5969e12f3185e8cb8eb08b871c9084 upstream.

The scanner (here DS3508) always returns 64 bytes per urb buffer. The first
byte indicates the data length used in the current buffer. There even was
a comment describing this. But the comment also said that we'll send
everything in the buffer to the tty layer. That means sending the actual
barcode data and lots of trailing zeroes. This patch lets the driver only
send the real data.

Signed-off-by: Philipp Hachtmann <hachti@xxxxxxxxx>
Acked-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Oliver Neukum <ONeukum@xxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/usb/serial/symbolserial.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/serial/symbolserial.c b/drivers/usb/serial/symbolserial.c
index 1e2d86d4f539..aa6d2bea856b 100644
--- a/drivers/usb/serial/symbolserial.c
+++ b/drivers/usb/serial/symbolserial.c
@@ -61,17 +61,15 @@ static void symbol_int_callback(struct urb *urb)
 
 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
 
+	/*
+	 * Data from the device comes with a 1 byte header:
+	 *
+	 * <size of data> <data>...
+	 */
 	if (urb->actual_length > 1) {
-		data_length = urb->actual_length - 1;
-
-		/*
-		 * Data from the device comes with a 1 byte header:
-		 *
-		 * <size of data>data...
-		 * 	This is real data to be sent to the tty layer
-		 * we pretty much just ignore the size and send everything
-		 * else to the tty layer.
-		 */
+		data_length = data[0];
+		if (data_length > (urb->actual_length - 1))
+			data_length = urb->actual_length - 1;
 		tty_insert_flip_string(&port->port, &data[1], data_length);
 		tty_flip_buffer_push(&port->port);
 	} else {
-- 
2.6.2

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