Commit message: atl2: Disable unimplemented scatter/gather feature

atl2 includes NETIF_F_SG in hw_features even though it has no support
for non-linear skbs.  This bug was originally harmless since the
driver does not claim to implement checksum offload and that used to
be a requirement for SG.

Now that SG and checksum offload are independent features, if you
explicitly enable SG *and* use one of the rare protocols that can use
SG without checkusm offload, this potentially leaks sensitive
information (before you notice that it just isn't working).  Therefore
this obscure bug has been designated CVE-2016-2117.

Reported-by: Justin Yackoski <jyackoski@crypto-nite.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: ec5f06156423 ("net: Kill link between CSUM and SG features.")
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2016-2117
CWE: CWE-200
Vulnerability description: The atl2_probe function in drivers/net/ethernet/atheros/atlx/atl2.c in the Linux kernel through 4.5.2 incorrectly enables scatter/gather I/O, which allows remote attackers to obtain sensitive information from kernel memory by reading packet data.

Project: linux
File: atl2.c

static int atl2_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
	struct net_device *netdev;
	struct atl2_adapter *adapter;
	static int cards_found;
	unsigned long mmio_start;
	int mmio_len;
	int err;

	cards_found = 0;

	err = pci_enable_device(pdev);
	if (err)
		return err;

	/*
	 * atl2 is a shared-high-32-bit device, so we're stuck with 32-bit DMA
	 * until the kernel has the proper infrastructure to support 64-bit DMA
	 * on these devices.
	 */
	if (pci_set_dma_mask(pdev, DMA_BIT_MASK(32)) &&
		pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32))) {
		printk(KERN_ERR "atl2: No usable DMA configuration, aborting\n");
		goto err_dma;
	}

	/* Mark all PCI regions associated with PCI device
	 * pdev as being reserved by owner atl2_driver_name */
	err = pci_request_regions(pdev, atl2_driver_name);
	if (err)
		goto err_pci_reg;

	/* Enables bus-mastering on the device and calls
	 * pcibios_set_master to do the needed arch specific settings */
	pci_set_master(pdev);

	err = -ENOMEM;
	netdev = alloc_etherdev(sizeof(struct atl2_adapter));
	if (!netdev)
		goto err_alloc_etherdev;

	SET_NETDEV_DEV(netdev, &pdev->dev);

	pci_set_drvdata(pdev, netdev);
	adapter = netdev_priv(netdev);
	adapter->netdev = netdev;
	adapter->pdev = pdev;
	adapter->hw.back = adapter;

	mmio_start = pci_resource_start(pdev, 0x0);
	mmio_len = pci_resource_len(pdev, 0x0);

	adapter->hw.mem_rang = (u32)mmio_len;
	adapter->hw.hw_addr = ioremap(mmio_start, mmio_len);
	if (!adapter->hw.hw_addr) {
		err = -EIO;
		goto err_ioremap;
	}

	atl2_setup_pcicmd(pdev);

	netdev->netdev_ops = &atl2_netdev_ops;
	netdev->ethtool_ops = &atl2_ethtool_ops;
	netdev->watchdog_timeo = 5 * HZ;
	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);

	netdev->mem_start = mmio_start;
	netdev->mem_end = mmio_start + mmio_len;
	adapter->bd_number = cards_found;
	adapter->pci_using_64 = false;

	/* setup the private structure */
	err = atl2_sw_init(adapter);
	if (err)
		goto err_sw_init;
 
 	err = -EIO;
 
	netdev->hw_features = NETIF_F_SG | NETIF_F_HW_VLAN_CTAG_RX;
 	netdev->features |= (NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_CTAG_RX);
 
 	/* Init PHY as early as possible due to power saving issue  */
	atl2_phy_init(&adapter->hw);

	/* reset the controller to
	 * put the device in a known good starting state */

	if (atl2_reset_hw(&adapter->hw)) {
		err = -EIO;
		goto err_reset;
	}

	/* copy the MAC address out of the EEPROM */
	atl2_read_mac_addr(&adapter->hw);
	memcpy(netdev->dev_addr, adapter->hw.mac_addr, netdev->addr_len);
	if (!is_valid_ether_addr(netdev->dev_addr)) {
		err = -EIO;
		goto err_eeprom;
	}

	atl2_check_options(adapter);

	setup_timer(&adapter->watchdog_timer, atl2_watchdog,
		    (unsigned long)adapter);

	setup_timer(&adapter->phy_config_timer, atl2_phy_config,
		    (unsigned long)adapter);

	INIT_WORK(&adapter->reset_task, atl2_reset_task);
	INIT_WORK(&adapter->link_chg_task, atl2_link_chg_task);

	strcpy(netdev->name, "eth%d"); /* ?? */
	err = register_netdev(netdev);
	if (err)
		goto err_register;

	/* assume we have no link for now */
	netif_carrier_off(netdev);
	netif_stop_queue(netdev);

	cards_found++;

	return 0;

err_reset:
err_register:
err_sw_init:
err_eeprom:
	iounmap(adapter->hw.hw_addr);
err_ioremap:
	free_netdev(netdev);
err_alloc_etherdev:
	pci_release_regions(pdev);
err_pci_reg:
err_dma:
	pci_disable_device(pdev);
	return err;
}