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

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

[Russell King (Oracle)]

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
Tested-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 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 d8b68145f6b4..8c59eb6a2b68 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -961,8 +961,14 @@ EXPORT_SYMBOL_GPL(mdiobus_modify_changed);
  */
 static int mdio_bus_match(struct device *dev, struct device_driver *drv)
 {
+	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
 	struct mdio_device *mdio = to_mdio_device(dev);
 
+	/* Both the driver and device must type-match */
+	if (!(mdiodrv->mdiodrv.flags & MDIO_DEVICE_IS_PHY) !=
+	    !(mdio->flags & MDIO_DEVICE_FLAG_PHY))
+		return 0;
+
 	if (of_driver_match_device(dev, drv))
 		return 1;
 
-- 
2.30.2

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

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Thu, 07 Oct 2021 14:23:27 +0100 you 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.)
> 
> [...]

Here is the summary with links:
  - [net-next] net: mdio: ensure the type of mdio devices match mdio drivers
    https://git.kernel.org/netdev/net-next/c/94114d90037f

You are awesome, thank you!
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