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    Subject[PATCH 4.9 10/20] Revert "net: mdiobus: Fix memory leak in __mdiobus_register"
    Date
    From: Pavel Skripkin <paskripkin@gmail.com>

    commit 10eff1f5788b6ffac212c254e2f3666219576889 upstream.

    This reverts commit ab609f25d19858513919369ff3d9a63c02cd9e2e.

    This patch is correct in the sense that we _should_ call device_put() in
    case of device_register() failure, but the problem in this code is more
    vast.

    We need to set bus->state to UNMDIOBUS_REGISTERED before calling
    device_register() to correctly release the device in mdiobus_free().
    This patch prevents us from doing it, since in case of device_register()
    failure put_device() will be called 2 times and it will cause UAF or
    something else.

    Also, Reported-by: tag in revered commit was wrong, since syzbot
    reported different leak in same function.

    Link: https://lore.kernel.org/netdev/20210928092657.GI2048@kadam/
    Acked-by: Yanfei Xu <yanfei.xu@windriver.com>
    Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
    Link: https://lore.kernel.org/r/f12fb1faa4eccf0f355788225335eb4309ff2599.1633024062.git.paskripkin@gmail.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/net/phy/mdio_bus.c | 1 -
    1 file changed, 1 deletion(-)

    --- a/drivers/net/phy/mdio_bus.c
    +++ b/drivers/net/phy/mdio_bus.c
    @@ -326,7 +326,6 @@ int __mdiobus_register(struct mii_bus *b
    err = device_register(&bus->dev);
    if (err) {
    pr_err("mii_bus %s failed to register\n", bus->id);
    - put_device(&bus->dev);
    return -EINVAL;
    }


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