Code: static void hid_input_field(struct hid_device *hid, struct hid_field *field,
			    __u8 *data, int interrupt)
{
	unsigned n;
	unsigned count = field->report_count;
	unsigned offset = field->report_offset;
	unsigned size = field->report_size;
	__s32 min = field->logical_minimum;
	__s32 max = field->logical_maximum;
	__s32 *value;

	value = kmalloc(sizeof(__s32) * count, GFP_ATOMIC);
	if (!value)
		return;

	for (n = 0; n < count; n++) {

		value[n] = min < 0 ?
			snto32(hid_field_extract(hid, data, offset + n * size,
			       size), size) :
			hid_field_extract(hid, data, offset + n * size, size);

 		/* Ignore report if ErrorRollOver */
 		if (!(field->flags & HID_MAIN_ITEM_VARIABLE) &&
 		    value[n] >= min && value[n] <= max &&
 		    field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1)
 			goto exit;
 	}

	for (n = 0; n < count; n++) {

		if (HID_MAIN_ITEM_VARIABLE & field->flags) {
			hid_process_event(hid, field, &field->usage[n], value[n], interrupt);
			continue;
 		}
 
 		if (field->value[n] >= min && field->value[n] <= max
 			&& field->usage[field->value[n] - min].hid
 			&& search(value, field->value[n], count))
 				hid_process_event(hid, field, &field->usage[field->value[n] - min], 0, interrupt);
 
 		if (value[n] >= min && value[n] <= max
 			&& field->usage[value[n] - min].hid
 			&& search(field->value, value[n], count))
 				hid_process_event(hid, field, &field->usage[value[n] - min], 1, interrupt);
	}

	memcpy(field->value, value, count * sizeof(__s32));
exit:
	kfree(value);
}

Commit Message: HID: core: prevent out-of-bound readings

Plugging a Logitech DJ receiver with KASAN activated raises a bunch of
out-of-bound readings.

The fields are allocated up to MAX_USAGE, meaning that potentially, we do
not have enough fields to fit the incoming values.
Add checks and silence KASAN.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
CWE ID: CWE-125
static void hid_input_field(struct hid_device *hid, struct hid_field *field,
			    __u8 *data, int interrupt)
{
	unsigned n;
	unsigned count = field->report_count;
	unsigned offset = field->report_offset;
	unsigned size = field->report_size;
	__s32 min = field->logical_minimum;
	__s32 max = field->logical_maximum;
	__s32 *value;

	value = kmalloc(sizeof(__s32) * count, GFP_ATOMIC);
	if (!value)
		return;

	for (n = 0; n < count; n++) {

		value[n] = min < 0 ?
			snto32(hid_field_extract(hid, data, offset + n * size,
			       size), size) :
			hid_field_extract(hid, data, offset + n * size, size);

 		/* Ignore report if ErrorRollOver */
 		if (!(field->flags & HID_MAIN_ITEM_VARIABLE) &&
 		    value[n] >= min && value[n] <= max &&
		    value[n] - min < field->maxusage &&
 		    field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1)
 			goto exit;
 	}

	for (n = 0; n < count; n++) {

		if (HID_MAIN_ITEM_VARIABLE & field->flags) {
			hid_process_event(hid, field, &field->usage[n], value[n], interrupt);
			continue;
 		}
 
 		if (field->value[n] >= min && field->value[n] <= max
			&& field->value[n] - min < field->maxusage
 			&& field->usage[field->value[n] - min].hid
 			&& search(value, field->value[n], count))
 				hid_process_event(hid, field, &field->usage[field->value[n] - min], 0, interrupt);
 
 		if (value[n] >= min && value[n] <= max
			&& value[n] - min < field->maxusage
 			&& field->usage[value[n] - min].hid
 			&& search(field->value, value[n], count))
 				hid_process_event(hid, field, &field->usage[value[n] - min], 1, interrupt);
	}

	memcpy(field->value, value, count * sizeof(__s32));
exit:
	kfree(value);
}
