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Commit 7e3cc447 authored by Benjamin Tissoires's avatar Benjamin Tissoires Committed by Jiri Kosina
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HID: multitouch: do not use pointers towards hid-core 



The previous implementation registered a pointer towards hid-core
to the value of contact count. This is not safe and may be difficult
to debug if hid-core ever changes its implementation.
The use of regular indexes is a better choice.

Signed-off-by: default avatarBenjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent dc3e1d80

drivers/hid/hid-multitouch.c

+13 −6
Original line number Diff line number Diff line
@@ -84,7 +84,8 @@ struct mt_device { 
	struct mt_class mtclass;	/* our mt device class */

	struct mt_fields *fields;	/* temporary placeholder for storing the

					   multitouch fields */

	__s32 *contactcount;		/* contact count value in the report */

	int cc_index;	/* contact count field index in the report */

	int cc_value_index;	/* contact count value index in the field */

	unsigned last_field_index;	/* last field index of the report */

	unsigned last_slot_field;	/* the last field of a slot */

	unsigned mt_report_id;	/* the report ID of the multitouch device */
@@ -269,7 +270,7 @@ static ssize_t mt_set_quirks(struct device *dev, 


	td->mtclass.quirks = val;



	if (!td->contactcount)

	if (td->cc_index < 0)

		td->mtclass.quirks &= ~MT_QUIRK_CONTACT_CNT_ACCURATE;



	return count;
@@ -483,7 +484,8 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi, 
			td->last_field_index = field->index;

			return 1;

		case HID_DG_CONTACTCOUNT:

			td->contactcount = field->value + usage->usage_index;

			td->cc_index = field->index;

			td->cc_value_index = usage->usage_index;

			td->last_field_index = field->index;

			return 1;

		case HID_DG_CONTACTMAX:
@@ -701,8 +703,12 @@ static void mt_report(struct hid_device *hid, struct hid_report *report) 
	 * Includes multi-packet support where subsequent

	 * packets are sent with zero contactcount.

	 */

	if (td->contactcount && *td->contactcount)

		td->num_expected = *td->contactcount;

	if (td->cc_index >= 0) {

		struct hid_field *field = report->field[td->cc_index];

		int value = field->value[td->cc_value_index];

		if (value)

			td->num_expected = value;

	}



	for (r = 0; r < report->maxfield; r++) {

		field = report->field[r];
@@ -786,7 +792,7 @@ static void mt_post_parse(struct mt_device *td) 
		td->last_slot_field = f->usages[field_count_per_touch - 1];

	}



	if (!td->contactcount)

	if (td->cc_index < 0)

		cls->quirks &= ~MT_QUIRK_CONTACT_CNT_ACCURATE;

}
@@ -845,6 +851,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id) 
	td->mtclass = *mtclass;

	td->inputmode = -1;

	td->maxcontact_report_id = -1;

	td->cc_index = -1;

	hid_set_drvdata(hdev, td);



	td->fields = kzalloc(sizeof(struct mt_fields), GFP_KERNEL);