Re: [PATCH 1/2] net: phy: Check phydev->drv before dereferencing it

[Russell King (Oracle)]

On Sun, Nov 26, 2023 at 04:10:45PM +0200, Claudiu Beznea wrote:
> The macb driver calls mdiobus_unregister() and mdiobus_free() in its remove
> function before calling unregister_netdev(). unregister_netdev() calls the
> driver-specific struct net_device_ops::ndo_stop function (macb_close()),
> and macb_close() calls phylink_disconnect_phy(). This, in turn, will call:
> 
> phy_disconnect() ->
>   phy_free_interrupt() ->
>     phy_disable_interrupts() ->
>       phy_config_interrupt()
> 
> which dereference phydev->drv, which was already freed by:
> mdiobus_unregister() ->
>   phy_mdio_device_remove() ->
>     device_del() ->
>       bus_remove_device() ->
>         device_release_driver_internal() ->
>           phy_remove()
> 
> from macb_close().
> 
> Although the sequence in the macb driver is not correct, check phydev->drv      
> before dereferencing it in phy_config_interrupt() to avoid scenarios
> like the one described.

I don't know why I've ended up with two copies of this series, but as
said in the other posting of this patch (where details of why can be
found)... NAK.

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