Input: zforce - don't overwrite the stack

If we get a corrupted packet with PAYLOAD_LENGTH > FRAME_MAXSIZE, we
will silently overwrite the stack.

Cc: stable@vger.kernel.org
Signed-off-by: Oleksij Rempel <external.Oleksij.Rempel@de.bosch.com>
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/zforce_ts.c

@@ -429,7 +429,7 @@ static int zforce_read_packet(struct zforce_ts *ts, u8 *buf)
 		goto unlock;
 	}
 
-	if (buf[PAYLOAD_LENGTH] == 0) {
+	if (buf[PAYLOAD_LENGTH] == 0 || buf[PAYLOAD_LENGTH] > FRAME_MAXSIZE) {
 		dev_err(&client->dev, "invalid payload length: %d\n",
 			buf[PAYLOAD_LENGTH]);
 		ret = -EIO;