static int sas_rediscover_dev(struct domain_device *dev, int phy_id, bool last)
{
	struct expander_device *ex = &dev->ex_dev;
	struct ex_phy *phy = &ex->ex_phy[phy_id];
	enum sas_device_type type = SAS_PHY_UNUSED;
	u8 sas_addr[8];
	int res;

	memset(sas_addr, 0, 8);
	res = sas_get_phy_attached_dev(dev, phy_id, sas_addr, &type);
	switch (res) {
	case SMP_RESP_NO_PHY:
		phy->phy_state = PHY_NOT_PRESENT;
		sas_unregister_devs_sas_addr(dev, phy_id, last);
		return res;
	case SMP_RESP_PHY_VACANT:
		phy->phy_state = PHY_VACANT;
		sas_unregister_devs_sas_addr(dev, phy_id, last);
		return res;
	case SMP_RESP_FUNC_ACC:
		break;
	case -ECOMM:
		break;
	default:
		return res;
	}

	if ((SAS_ADDR(sas_addr) == 0) || (res == -ECOMM)) {
		phy->phy_state = PHY_EMPTY;
		sas_unregister_devs_sas_addr(dev, phy_id, last);
		return res;
	} else if (SAS_ADDR(sas_addr) == SAS_ADDR(phy->attached_sas_addr) &&
		   dev_type_flutter(type, phy->attached_dev_type)) {
		struct domain_device *ata_dev = sas_ex_to_ata(dev, phy_id);
		char *action = "";

		sas_ex_phy_discover(dev, phy_id);

		if (ata_dev && phy->attached_dev_type == SAS_SATA_PENDING)
			action = ", needs recovery";
		SAS_DPRINTK("ex %016llx phy 0x%x broadcast flutter%s\n",
			    SAS_ADDR(dev->sas_addr), phy_id, action);
		return res;
	}

	/* we always have to delete the old device when we went here */
	SAS_DPRINTK("ex %016llx phy 0x%x replace %016llx\n",
		    SAS_ADDR(dev->sas_addr), phy_id,
		    SAS_ADDR(phy->attached_sas_addr));
	sas_unregister_devs_sas_addr(dev, phy_id, last);

	return sas_discover_new(dev, phy_id);
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.