HID: multitouch: Fix fields from pen report ID being interpreted for multitouch
Fields like HID_DG_CONTACTCOUNT are outside of the physical collection,
but within the application collection and report ID. Make sure to catch
those fields that are not part of the mt_report_id and return 0 so they
can be processed with the pen. Otherwise, the wrong HID_DG_CONTACTCOUNT
will be applied to cc_index and result in dereferencing a null pointer in
mt_touch_report.
Signed-off-by: Brent Adam <brentadam@smarttech.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 6a9b05b..7c81125 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -778,9 +778,16 @@
/*
* some egalax touchscreens have "application == HID_DG_TOUCHSCREEN"
* for the stylus.
+ * The check for mt_report_id ensures we don't process
+ * HID_DG_CONTACTCOUNT from the pen report as it is outside the physical
+ * collection, but within the report ID.
*/
if (field->physical == HID_DG_STYLUS)
return 0;
+ else if ((field->physical == 0) &&
+ (field->report->id != td->mt_report_id) &&
+ (td->mt_report_id != -1))
+ return 0;
if (field->application == HID_DG_TOUCHSCREEN ||
field->application == HID_DG_TOUCHPAD)