[PATCH 4.6 40/96] Input: wacom_w8001 - ignore invalid pen data packets

[Greg Kroah-Hartman]

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

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

From: Ping Cheng <pinglinux@xxxxxxxxx>

commit 9e72ac7492149a229ce9039c680849cb682d7092 upstream.

ThinkPad X60 Tablet PC (pen only device) sometime posts
packets that are larger than W8001_PKTLEN_TPCPEN.

Reported-by: Chris J Arges <christopherarges@xxxxxxxxx>
Tested-by: Chris J Arges <christopherarges@xxxxxxxxx>
Signed-off-by: Ping Cheng <pingc@xxxxxxxxx>
Reviewed-by: Peter Hutterer <peter.hutterer@xxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/input/touchscreen/wacom_w8001.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c
@@ -339,6 +339,15 @@ static irqreturn_t w8001_interrupt(struc
 		w8001->idx = 0;
 		parse_multi_touch(w8001);
 		break;
+
+	default:
+		/*
+		 * ThinkPad X60 Tablet PC (pen only device) sometimes
+		 * sends invalid data packets that are larger than
+		 * W8001_PKTLEN_TPCPEN. Let's start over again.
+		 */
+		if (!w8001->touch_dev && w8001->idx > W8001_PKTLEN_TPCPEN - 1)
+			w8001->idx = 0;
 	}
 
 	return IRQ_HANDLED;