nfc: Ensure presence of required attributes in the deactivate_target handler

Check that the NFC_ATTR_TARGET_INDEX attributes (in addition to
NFC_ATTR_DEVICE_INDEX) are provided by the netlink client prior to
accessing them. This prevents potential unhandled NULL pointer dereference
exceptions which can be triggered by malicious user-mode programs,
if they omit one or both of these attributes.

Signed-off-by: Young Xiao <92siuyang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
int nfc_genl_se_connectivity(struct nfc_dev *dev, u8 se_idx)
{
	struct nfc_se *se;
	struct sk_buff *msg;
	void *hdr;

	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
	if (!msg)
		return -ENOMEM;

	hdr = genlmsg_put(msg, 0, 0, &nfc_genl_family, 0,
			  NFC_EVENT_SE_CONNECTIVITY);
	if (!hdr)
		goto free_msg;

	se = nfc_find_se(dev, se_idx);
	if (!se)
		goto free_msg;

	if (nla_put_u32(msg, NFC_ATTR_DEVICE_INDEX, dev->idx) ||
	    nla_put_u32(msg, NFC_ATTR_SE_INDEX, se_idx) ||
	    nla_put_u8(msg, NFC_ATTR_SE_TYPE, se->type))
		goto nla_put_failure;

	genlmsg_end(msg, hdr);

	genlmsg_multicast(&nfc_genl_family, msg, 0, 0, GFP_KERNEL);

	return 0;

nla_put_failure:
free_msg:
	nlmsg_free(msg);
	return -EMSGSIZE;
}

int nfc_genl_se_connectivity(struct nfc_dev *dev, u8 se_idx)
{
	struct nfc_se *se;
	struct sk_buff *msg;
	void *hdr;

	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
	if (!msg)
		return -ENOMEM;

	hdr = genlmsg_put(msg, 0, 0, &nfc_genl_family, 0,
			  NFC_EVENT_SE_CONNECTIVITY);
	if (!hdr)
		goto free_msg;

	se = nfc_find_se(dev, se_idx);
	if (!se)
		goto free_msg;

	if (nla_put_u32(msg, NFC_ATTR_DEVICE_INDEX, dev->idx) ||
	    nla_put_u32(msg, NFC_ATTR_SE_INDEX, se_idx) ||
	    nla_put_u8(msg, NFC_ATTR_SE_TYPE, se->type))
		goto nla_put_failure;

	genlmsg_end(msg, hdr);

	genlmsg_multicast(&nfc_genl_family, msg, 0, 0, GFP_KERNEL);

	return 0;

nla_put_failure:
free_msg:
	nlmsg_free(msg);
	return -EMSGSIZE;
}
