popo:: linux kernel vulns of it.

[KJ Jung <x90cx90c1 () gmail com>]

I reproduce the report and i can audit it.
bond_do_ioctl funtion in the bonding net driver of linux kernel 5.4.
it has a bug of stack buffer overflow.
I will show it for you to know or understanding help to know kernel hacks.

buffer overflow in bonding drivers.
latest.

----
https://lxr.missinglinkelectronics.com/linux/drivers/net/bonding/bond_main.c#L1051
3
469static int bond_do_ioctl(struct net_device *bond_dev, struct ifreq *ifr,
int cmd)
3470{
3471        struct bonding *bond = netdev_priv(bond_dev);
3472        struct net_device *slave_dev = NULL; // [1]:: ... net_device
*slave_dev!
3473        struct ifbond k_binfo;
3474        struct ifbond __user *u_binfo = NULL;
3475        struct ifslave k_sinfo;
3476        struct ifslave __user *u_sinfo = NULL;
3477        struct mii_ioctl_data *mii = NULL;
3478        struct bond_opt_value newval;
3479        struct net *net;
3480        int res = 0;
3481
3482        netdev_dbg(bond_dev, "bond_ioctl: cmd=%d\n", cmd);
3483
3484        switch (cmd) {
3485        case SIOCGMIIPHY:
3486                mii = if_mii(ifr);
3487                if (!mii)
3488                        return -EINVAL;
3489
3490                mii->phy_id = 0;
3491                /* Fall Through */
3492        case SIOCGMIIREG:
3493                /* We do this again just in case we were called by
SIOCGMIIREG
3494                 * instead of SIOCGMIIPHY.
3495                 */
3496                mii = if_mii(ifr);
3497                if (!mii)
3498                        return -EINVAL;
3499
3500                if (mii->reg_num == 1) {
3501                        mii->val_out = 0;
3502                        if (netif_carrier_ok(bond->dev))
3503                                mii->val_out = BMSR_LSTATUS;
3504                }
3505
3506                return 0;
3507        case BOND_INFO_QUERY_OLD:
3508        case SIOCBONDINFOQUERY:
3509                u_binfo = (struct ifbond __user *)ifr->ifr_data;
3510
3511                if (copy_from_user(&k_binfo, u_binfo, sizeof(ifbond)))
3512                        return -EFAULT;
3513
3514                bond_info_query(bond_dev, &k_binfo);
3515                if (copy_to_user(u_binfo, &k_binfo, sizeof(ifbond)))
3516                        return -EFAULT;
3517
3518                return 0;
3519        case BOND_SLAVE_INFO_QUERY_OLD:
3520        case SIOCBONDSLAVEINFOQUERY:
3521                u_sinfo = (struct ifslave __user *)ifr->ifr_data;
3522
3523                if (copy_from_user(&k_sinfo, u_sinfo, sizeof(ifslave)))
3524                        return -EFAULT;
3525
3526                res = bond_slave_info_query(bond_dev, &k_sinfo);
3527                if (res == 0 &&
3528                    copy_to_user(u_sinfo, &k_sinfo, sizeof(ifslave)))
3529                        return -EFAULT;
3530
3531                return res;
3532        default:
3533                break;
3534        }
3535
3536        net = dev_net(bond_dev);
3537
3538        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
3539                return -EPERM;
3540
            // [2]:: slave_dev = ifr->ifr_slave (user controlled)
3541        slave_dev = __dev_get_by_name(net, ifr->ifr_slave);
3542
3543        slave_dbg(bond_dev, slave_dev, "slave_dev=%p:\n", slave_dev);
3544
3545        if (!slave_dev)
3546                return -ENODEV;
3547
3548        switch (cmd) {
3549        case BOND_ENSLAVE_OLD:
3550        case SIOCBONDENSLAVE:
3551                res = bond_enslave(bond_dev, slave_dev, NULL);
3552                break;
3553        case BOND_RELEASE_OLD:
3554        case SIOCBONDRELEASE:
3555                res = bond_release(bond_dev, slave_dev);
3556                break;
3557        case BOND_SETHWADDR_OLD:
3558        case SIOCBONDSETHWADDR:
                    // [3]:: SIOCBONDSETHWADDR case enter to vulnerable
function bond_set_dev_addr with slave_dev.
3559                res = bond_set_dev_addr(bond_dev, slave_dev);
3560                break;
3561        case BOND_CHANGE_ACTIVE_OLD:
3562        case SIOCBONDCHANGEACTIVE:
3563                bond_opt_initstr(&newval, slave_dev->name);
3564                res = __bond_opt_set_notify(bond, BOND_OPT_ACTIVE_SLAVE,
3565                                            &newval);
3566                break;
3567        default:
3568                res = -EOPNOTSUPP;
3569        }
3570
3571        return res;
3572}


 604/**
 605 * bond_set_dev_addr - clone slave's address to bond
 606 * @bond_dev: bond net device
 607 * @slave_dev: slave net device
 608 *
 609 * Should be called with RTNL held.
 610 */
 611static int bond_set_dev_addr(struct net_device *bond_dev,
 612                             struct net_device *slave_dev)
 613{
 614        int err;
 615
 616        slave_dbg(bond_dev, slave_dev, "bond_dev=%p slave_dev=%p
slave_dev->addr_len=%d\n",
 617                  bond_dev, slave_dev, slave_dev->addr_len);
 618        err = dev_pre_changeaddr_notify(bond_dev, slave_dev->dev_addr,
NULL);
 619        if (err)
 620                return err;
 621
            // [4]:: x90: Trigger point: slave_dev->dev_addr,
slave_dev->addr_len two variables controlled by user in memcpy
                     API.
 622        memcpy(bond_dev->dev_addr, slave_dev->dev_addr,
slave_dev->addr_len);
 623        bond_dev->addr_assign_type = NET_ADDR_STOLEN;
 624        call_netdevice_notifiers(NETDEV_CHANGEADDR, bond_dev);
 625        return 0;
 626}
 627
--------


--Author:: x90

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