Input: wacom_w8001 - ignore invalid pen data packets

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

Reported-by: Chris J Arges <christopherarges@gmail.com>
Tested-by: Chris J Arges <christopherarges@gmail.com>
Signed-off-by: Ping Cheng <pingc@wacom.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index b1b412766da8..0c9191cf324d 100644
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c
@@ -339,6 +339,15 @@ static irqreturn_t w8001_interrupt(struct serio *serio,
                 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;