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    Subject[PATCH 4.9 08/39] tun: call dev_get_valid_name() before register_netdevice()
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

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

    From: Cong Wang <xiyou.wangcong@gmail.com>


    [ Upstream commit 0ad646c81b2182f7fa67ec0c8c825e0ee165696d ]

    register_netdevice() could fail early when we have an invalid
    dev name, in which case ->ndo_uninit() is not called. For tun
    device, this is a problem because a timer etc. are already
    initialized and it expects ->ndo_uninit() to clean them up.

    We could move these initializations into a ->ndo_init() so
    that register_netdevice() knows better, however this is still
    complicated due to the logic in tun_detach().

    Therefore, I choose to just call dev_get_valid_name() before
    register_netdevice(), which is quicker and much easier to audit.
    And for this specific case, it is already enough.

    Fixes: 96442e42429e ("tuntap: choose the txq based on rxq")
    Reported-by: Dmitry Alexeev <avekceeb@gmail.com>
    Cc: Jason Wang <jasowang@redhat.com>
    Cc: "Michael S. Tsirkin" <mst@redhat.com>
    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/tun.c | 3 +++
    include/linux/netdevice.h | 3 +++
    net/core/dev.c | 6 +++---
    3 files changed, 9 insertions(+), 3 deletions(-)

    --- a/drivers/net/tun.c
    +++ b/drivers/net/tun.c
    @@ -1787,6 +1787,9 @@ static int tun_set_iff(struct net *net,

    if (!dev)
    return -ENOMEM;
    + err = dev_get_valid_name(net, dev, name);
    + if (err)
    + goto err_free_dev;

    dev_net_set(dev, net);
    dev->rtnl_link_ops = &tun_link_ops;
    --- a/include/linux/netdevice.h
    +++ b/include/linux/netdevice.h
    @@ -3742,6 +3742,9 @@ struct net_device *alloc_netdev_mqs(int
    unsigned char name_assign_type,
    void (*setup)(struct net_device *),
    unsigned int txqs, unsigned int rxqs);
    +int dev_get_valid_name(struct net *net, struct net_device *dev,
    + const char *name);
    +
    #define alloc_netdev(sizeof_priv, name, name_assign_type, setup) \
    alloc_netdev_mqs(sizeof_priv, name, name_assign_type, setup, 1, 1)

    --- a/net/core/dev.c
    +++ b/net/core/dev.c
    @@ -1115,9 +1115,8 @@ static int dev_alloc_name_ns(struct net
    return ret;
    }

    -static int dev_get_valid_name(struct net *net,
    - struct net_device *dev,
    - const char *name)
    +int dev_get_valid_name(struct net *net, struct net_device *dev,
    + const char *name)
    {
    BUG_ON(!net);

    @@ -1133,6 +1132,7 @@ static int dev_get_valid_name(struct net

    return 0;
    }
    +EXPORT_SYMBOL(dev_get_valid_name);

    /**
    * dev_change_name - change name of a device

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