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    Subject[patch 09/76] NET: Fix race in dev_close(). (Bug 9750)
    -stable review patch.  If anyone has any objections, please let us know.
    ---------------------

    From: Matti Linnanvuori <mattilinnanvuori@yahoo.com>

    Upstream commit: d8b2a4d21e0b37b9669b202867bfef19f68f786a

    There is a race in Linux kernel file net/core/dev.c, function dev_close.
    The function calls function dev_deactivate, which calls function
    dev_watchdog_down that deletes the watchdog timer. However, after that, a
    driver can call netif_carrier_ok, which calls function
    __netdev_watchdog_up that can add the watchdog timer again. Function
    unregister_netdevice calls function dev_shutdown that traps the bug
    !timer_pending(&dev->watchdog_timer). Moving dev_deactivate after
    netif_running() has been cleared prevents function netif_carrier_on
    from calling __netdev_watchdog_up and adding the watchdog timer again.

    Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    Signed-off-by: Chris Wright <chrisw@sous-sol.org>

    ---
    net/core/dev.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/net/core/dev.c
    +++ b/net/core/dev.c
    @@ -1068,8 +1068,6 @@ int dev_close(struct net_device *dev)
    */
    call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);

    - dev_deactivate(dev);
    -
    clear_bit(__LINK_STATE_START, &dev->state);

    /* Synchronize to scheduled poll. We cannot touch poll list,
    @@ -1080,6 +1078,8 @@ int dev_close(struct net_device *dev)
    */
    smp_mb__after_clear_bit(); /* Commit netif_running(). */

    + dev_deactivate(dev);
    +
    /*
    * Call the device specific close. This cannot fail.
    * Only if device is UP
    --


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