static s32 item_sdata(struct hid_item *item)
{
	switch (item->size) {
	case 1: return item->data.s8;
	case 2: return item->data.s16;
	case 4: return item->data.s32;
	}
	return 0;
}

The product reads data past the end, or before the beginning, of the intended buffer.