netdev - Re: [PATCH net 1/2] net: phy: Avoid NPD upon phy

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Message-ID: <20200917131545.GL3526428@lunn.ch>
Date:   Thu, 17 Sep 2020 15:15:45 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     netdev@...r.kernel.org, hkallweit1@...il.com, kuba@...nel.org,
        davem@...emloft.net
Subject: Re: [PATCH net 1/2] net: phy: Avoid NPD upon phy_detach() when
 driver is unbound

On Wed, Sep 16, 2020 at 08:43:09PM -0700, Florian Fainelli wrote:
> If we have unbound the PHY driver prior to calling phy_detach() (often
> via phy_disconnect()) then we can cause a NULL pointer de-reference
> accessing the driver owner member. The steps to reproduce are:
> 
> echo unimac-mdio-0:01 > /sys/class/net/eth0/phydev/driver/unbind
> ip link set eth0 down

Hi Florian

How forceful is this unbind? Can we actually block it while the
interface is up? Or returning -EBUSY would make sense.

	  Andrew