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    Subject[PATCH 4.4 30/48] rtnl: limit IFLA_NUM_TX_QUEUES and IFLA_NUM_RX_QUEUES to 4096
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Dumazet <edumazet@google.com>

    [ Upstream commit 0e1d6eca5113858ed2caea61a5adc03c595f6096 ]

    We have an impressive number of syzkaller bugs that are linked
    to the fact that syzbot was able to create a networking device
    with millions of TX (or RX) queues.

    Let's limit the number of RX/TX queues to 4096, this really should
    cover all known cases.

    A separate patch will add various cond_resched() in the loops
    handling sysfs entries at device creation and dismantle.

    Tested:

    lpaa6:~# ip link add gre-4097 numtxqueues 4097 numrxqueues 4097 type ip6gretap
    RTNETLINK answers: Invalid argument

    lpaa6:~# time ip link add gre-4096 numtxqueues 4096 numrxqueues 4096 type ip6gretap

    real 0m0.180s
    user 0m0.000s
    sys 0m0.107s

    Fixes: 76ff5cc91935 ("rtnl: allow to specify number of rx and tx queues on device creation")
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Reported-by: syzbot <syzkaller@googlegroups.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/core/rtnetlink.c | 6 ++++++
    1 file changed, 6 insertions(+)

    --- a/net/core/rtnetlink.c
    +++ b/net/core/rtnetlink.c
    @@ -2116,6 +2116,12 @@ struct net_device *rtnl_create_link(stru
    else if (ops->get_num_rx_queues)
    num_rx_queues = ops->get_num_rx_queues();

    + if (num_tx_queues < 1 || num_tx_queues > 4096)
    + return ERR_PTR(-EINVAL);
    +
    + if (num_rx_queues < 1 || num_rx_queues > 4096)
    + return ERR_PTR(-EINVAL);
    +
    err = -ENOMEM;
    dev = alloc_netdev_mqs(ops->priv_size, ifname, name_assign_type,
    ops->setup, num_tx_queues, num_rx_queues);

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