static int nfc_genl_deactivate_target(struct sk_buff *skb,
				      struct genl_info *info)
{
	struct nfc_dev *dev;
	u32 device_idx, target_idx;
	int rc;

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

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

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

	target_idx = nla_get_u32(info->attrs[NFC_ATTR_TARGET_INDEX]);

	rc = nfc_deactivate_target(dev, target_idx, NFC_TARGET_MODE_SLEEP);

	nfc_put_device(dev);
	return rc;
}
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.