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    SubjectRe: Possible race in nsc-ircc.ko
    On Fri, Aug 25, 2017 at 05:05:25PM +0300, Anton Volkov wrote:
    > Hello.
    >
    > While searching for races in the Linux kernel I've come across
    > "drivers/net/irda/nsc-ircc.ko" module. Here is a question that I came up
    > with while analyzing results. Lines are given using the info from Linux
    > v4.12.
    >
    > Consider the following case:
    >
    > Thread 1: Thread 2:
    > nsc_ircc_init
    > ->nsc_ircc_open
    > self = netdev_priv(dev)
    > register_netdev(dev)
    > nsc_ircc_net_ioctl
    > ->nsc_ircc_change_speed
    > self->dongle_id = ... <READ self->io.dongle_id>
    > (nsc-ircc.c: line 485) (nsc-ircc.c: line 1318)
    > platform_device_register_simple
    >
    > Before the initialization of self->dongle_id in msc_ircc_open() its value is
    > 0. Thus if read access to its value in nsc_ircc_change_speed occurs before
    > the initialization there will be an attempt to change speed of dongle with
    > undesired id (if the dongle with id 0 exists). Is this case feasible from
    > your point of view?
    >
    > Thank you for your time.
    >
    > -- Anton Volkov

    A first glance, that seems like a valid race. I'm not sure if
    there is a netdev lock/status to protect the driver, because it looks
    like doing any operation on a device before "open" has completed would
    be dangerous for most drivers.
    I don't have time to check the code paths, as I have not
    looked at that code in ages.
    Good luck !

    Jean

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