static int tg3_mdio_init(struct tg3 *tp)
{
	int i;
	u32 reg;
	struct phy_device *phydev;

	if (tg3_flag(tp, 5717_PLUS)) {
		u32 is_serdes;

		tp->phy_addr = tp->pci_fn + 1;

		if (tg3_chip_rev_id(tp) != CHIPREV_ID_5717_A0)
			is_serdes = tr32(SG_DIG_STATUS) & SG_DIG_IS_SERDES;
		else
			is_serdes = tr32(TG3_CPMU_PHY_STRAP) &
				    TG3_CPMU_PHY_STRAP_IS_SERDES;
		if (is_serdes)
			tp->phy_addr += 7;
	} else
		tp->phy_addr = TG3_PHY_MII_ADDR;

	tg3_mdio_start(tp);

	if (!tg3_flag(tp, USE_PHYLIB) || tg3_flag(tp, MDIOBUS_INITED))
		return 0;

	tp->mdio_bus = mdiobus_alloc();
	if (tp->mdio_bus == NULL)
		return -ENOMEM;

	tp->mdio_bus->name     = "tg3 mdio bus";
	snprintf(tp->mdio_bus->id, MII_BUS_ID_SIZE, "%x",
		 (tp->pdev->bus->number << 8) | tp->pdev->devfn);
	tp->mdio_bus->priv     = tp;
	tp->mdio_bus->parent   = &tp->pdev->dev;
	tp->mdio_bus->read     = &tg3_mdio_read;
	tp->mdio_bus->write    = &tg3_mdio_write;
	tp->mdio_bus->reset    = &tg3_mdio_reset;
	tp->mdio_bus->phy_mask = ~(1 << TG3_PHY_MII_ADDR);
	tp->mdio_bus->irq      = &tp->mdio_irq[0];

	for (i = 0; i < PHY_MAX_ADDR; i++)
		tp->mdio_bus->irq[i] = PHY_POLL;

	/* The bus registration will look for all the PHYs on the mdio bus.
	 * Unfortunately, it does not ensure the PHY is powered up before
	 * accessing the PHY ID registers.  A chip reset is the
	 * quickest way to bring the device back to an operational state..
	 */
	if (tg3_readphy(tp, MII_BMCR, &reg) || (reg & BMCR_PDOWN))
		tg3_bmcr_reset(tp);

	i = mdiobus_register(tp->mdio_bus);
	if (i) {
		dev_warn(&tp->pdev->dev, "mdiobus_reg failed (0x%x)\n", i);
		mdiobus_free(tp->mdio_bus);
		return i;
	}

	phydev = tp->mdio_bus->phy_map[TG3_PHY_MII_ADDR];

	if (!phydev || !phydev->drv) {
		dev_warn(&tp->pdev->dev, "No PHY devices\n");
		mdiobus_unregister(tp->mdio_bus);
		mdiobus_free(tp->mdio_bus);
		return -ENODEV;
	}

	switch (phydev->drv->phy_id & phydev->drv->phy_id_mask) {
	case PHY_ID_BCM57780:
		phydev->interface = PHY_INTERFACE_MODE_GMII;
		phydev->dev_flags |= PHY_BRCM_AUTO_PWRDWN_ENABLE;
		break;
	case PHY_ID_BCM50610:
	case PHY_ID_BCM50610M:
		phydev->dev_flags |= PHY_BRCM_CLEAR_RGMII_MODE |
				     PHY_BRCM_RX_REFCLK_UNUSED |
				     PHY_BRCM_DIS_TXCRXC_NOENRGY |
				     PHY_BRCM_AUTO_PWRDWN_ENABLE;
		if (tg3_flag(tp, RGMII_INBAND_DISABLE))
			phydev->dev_flags |= PHY_BRCM_STD_IBND_DISABLE;
		if (tg3_flag(tp, RGMII_EXT_IBND_RX_EN))
			phydev->dev_flags |= PHY_BRCM_EXT_IBND_RX_ENABLE;
		if (tg3_flag(tp, RGMII_EXT_IBND_TX_EN))
			phydev->dev_flags |= PHY_BRCM_EXT_IBND_TX_ENABLE;
		/* fallthru */
	case PHY_ID_RTL8211C:
		phydev->interface = PHY_INTERFACE_MODE_RGMII;
		break;
	case PHY_ID_RTL8201E:
	case PHY_ID_BCMAC131:
		phydev->interface = PHY_INTERFACE_MODE_MII;
		phydev->dev_flags |= PHY_BRCM_AUTO_PWRDWN_ENABLE;
		tp->phy_flags |= TG3_PHYFLG_IS_FET;
		break;
	}

	tg3_flag_set(tp, MDIOBUS_INITED);

	if (tg3_asic_rev(tp) == ASIC_REV_5785)
		tg3_mdio_config_5785(tp);

	return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.