netdev - Re: [PATCH RFT net-next] net: mdio: ensure the type of mdio devices match mdio drivers

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Message-ID: <YVXUmDkkTT3ihKh0@shell.armlinux.org.uk>
Date:   Thu, 30 Sep 2021 16:15:36 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH RFT net-next] net: mdio: ensure the type of mdio devices
 match mdio drivers

On Thu, Sep 30, 2021 at 04:58:53PM +0200, Andrew Lunn wrote:
> On Thu, Sep 30, 2021 at 03:54:44PM +0100, Russell King (Oracle) wrote:
> > On the MDIO bus, we have PHYLIB devices and drivers, and we have non-
> > PHYLIB devices and drivers. PHYLIB devices are MDIO devices that are
> > wrapped with a struct phy_device.
> > 
> > Trying to bind a MDIO device with a PHYLIB driver results in out-of-
> > bounds accesses as we attempt to access struct phy_device members. So,
> > let's prevent this by ensuring that the type of the MDIO device
> > (indicated by the MDIO_DEVICE_FLAG_PHY flag) matches the type of the
> > MDIO driver (indicated by the MDIO_DEVICE_IS_PHY flag.)
> > 
> > Link: https://lore.kernel.org/r/2b1dc053-8c9a-e3e4-b450-eecdfca3fe16@gmail.com
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> > ---
> > Tested locally in SolidRun Clearfog, DSA switch and PHY get probed
> > correctly. Further testing welcomed.
> > 
> >  drivers/net/phy/mdio_bus.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> > index 53f034fc2ef7..779e49715e91 100644
> > --- a/drivers/net/phy/mdio_bus.c
> > +++ b/drivers/net/phy/mdio_bus.c
> > @@ -939,6 +939,12 @@ EXPORT_SYMBOL_GPL(mdiobus_modify);
> >  static int mdio_bus_match(struct device *dev, struct device_driver *drv)
> >  {
> >  	struct mdio_device *mdio = to_mdio_device(dev);
> > +	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
> 
> DaveM would request these two lines are swapped for reverse Christmas tree.

Yep. I'll get around to that sometime.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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