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    Subject[PATCH 4.14 198/293] bonding: validate ip header before check IPPROTO_IGMP
    Date
    From: Cong Wang <xiyou.wangcong@gmail.com>

    [ Upstream commit 9d1bc24b52fb8c5d859f9a47084bf1179470e04c ]

    bond_xmit_roundrobin() checks for IGMP packets but it parses
    the IP header even before checking skb->protocol.

    We should validate the IP header with pskb_may_pull() before
    using iph->protocol.

    Reported-and-tested-by: syzbot+e5be16aa39ad6e755391@syzkaller.appspotmail.com
    Fixes: a2fd940f4cff ("bonding: fix broken multicast with round-robin mode")
    Cc: Jay Vosburgh <j.vosburgh@gmail.com>
    Cc: Veaceslav Falico <vfalico@gmail.com>
    Cc: Andy Gospodarek <andy@greyhouse.net>
    Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/net/bonding/bond_main.c | 37 +++++++++++++++++++++++--------------
    1 file changed, 23 insertions(+), 14 deletions(-)

    --- a/drivers/net/bonding/bond_main.c
    +++ b/drivers/net/bonding/bond_main.c
    @@ -3817,8 +3817,8 @@ static u32 bond_rr_gen_slave_id(struct b
    static int bond_xmit_roundrobin(struct sk_buff *skb, struct net_device *bond_dev)
    {
    struct bonding *bond = netdev_priv(bond_dev);
    - struct iphdr *iph = ip_hdr(skb);
    struct slave *slave;
    + int slave_cnt;
    u32 slave_id;

    /* Start with the curr_active_slave that joined the bond as the
    @@ -3827,23 +3827,32 @@ static int bond_xmit_roundrobin(struct s
    * send the join/membership reports. The curr_active_slave found
    * will send all of this type of traffic.
    */
    - if (iph->protocol == IPPROTO_IGMP && skb->protocol == htons(ETH_P_IP)) {
    - slave = rcu_dereference(bond->curr_active_slave);
    - if (slave)
    - bond_dev_queue_xmit(bond, skb, slave->dev);
    - else
    - bond_xmit_slave_id(bond, skb, 0);
    - } else {
    - int slave_cnt = ACCESS_ONCE(bond->slave_cnt);
    + if (skb->protocol == htons(ETH_P_IP)) {
    + int noff = skb_network_offset(skb);
    + struct iphdr *iph;
    +
    + if (unlikely(!pskb_may_pull(skb, noff + sizeof(*iph))))
    + goto non_igmp;

    - if (likely(slave_cnt)) {
    - slave_id = bond_rr_gen_slave_id(bond);
    - bond_xmit_slave_id(bond, skb, slave_id % slave_cnt);
    - } else {
    - bond_tx_drop(bond_dev, skb);
    + iph = ip_hdr(skb);
    + if (iph->protocol == IPPROTO_IGMP) {
    + slave = rcu_dereference(bond->curr_active_slave);
    + if (slave)
    + bond_dev_queue_xmit(bond, skb, slave->dev);
    + else
    + bond_xmit_slave_id(bond, skb, 0);
    + return NETDEV_TX_OK;
    }
    }

    +non_igmp:
    + slave_cnt = ACCESS_ONCE(bond->slave_cnt);
    + if (likely(slave_cnt)) {
    + slave_id = bond_rr_gen_slave_id(bond);
    + bond_xmit_slave_id(bond, skb, slave_id % slave_cnt);
    + } else {
    + bond_tx_drop(bond_dev, skb);
    + }
    return NETDEV_TX_OK;
    }


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