static int nfc_genl_dep_link_down(struct sk_buff *skb, struct genl_info *info)
{
	struct nfc_dev *dev;
	int rc;
	u32 idx;

	if (!info->attrs[NFC_ATTR_DEVICE_INDEX])
		return -EINVAL;

	idx = nla_get_u32(info->attrs[NFC_ATTR_DEVICE_INDEX]);

	dev = nfc_get_device(idx);
	if (!dev)
		return -ENODEV;

	rc = nfc_dep_link_down(dev);

	nfc_put_device(dev);
	return rc;
}

The product dereferences a pointer that it expects to be valid but is NULL.