netdev - Re: [PATCH net-next] net: phy: don't crash in phy_read/_write

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Date:   Thu, 16 Jan 2020 19:48:58 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Alex Marginean <alexandru.marginean@....com>
Subject: Re: [PATCH net-next] net: phy: don't crash in phy_read/_write_mmd
 without a PHY driver

On Thu, 16 Jan 2020 at 19:46, Vladimir Oltean <olteanv@...il.com> wrote:
>
> From: Alex Marginean <alexandru.marginean@....com>
>
> The APIs can be used by Ethernet drivers without actually loading a PHY
> driver. This may become more widespread in the future with 802.3z
> compatible MAC PCS devices being locally driven by the MAC driver when
> configuring for a PHY mode with in-band negotiation.
>
> Check that drv is not NULL before reading from it.
>
> Signed-off-by: Alex Marginean <alexandru.marginean@....com>
> ---

Ugh. Can I just add here:

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

without resending?

> If this hasn't been reported by now I assume it wasn't an issue so far.
> So I've targeted the patch for net-next and not provided a Fixes: tag.
>
>  drivers/net/phy/phy-core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
> index 769a076514b0..a4d2d59fceca 100644
> --- a/drivers/net/phy/phy-core.c
> +++ b/drivers/net/phy/phy-core.c
> @@ -387,7 +387,7 @@ int __phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum)
>         if (regnum > (u16)~0 || devad > 32)
>                 return -EINVAL;
>
> -       if (phydev->drv->read_mmd) {
> +       if (phydev->drv && phydev->drv->read_mmd) {
>                 val = phydev->drv->read_mmd(phydev, devad, regnum);
>         } else if (phydev->is_c45) {
>                 u32 addr = MII_ADDR_C45 | (devad << 16) | (regnum & 0xffff);
> @@ -444,7 +444,7 @@ int __phy_write_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val)
>         if (regnum > (u16)~0 || devad > 32)
>                 return -EINVAL;
>
> -       if (phydev->drv->write_mmd) {
> +       if (phydev->drv && phydev->drv->write_mmd) {
>                 ret = phydev->drv->write_mmd(phydev, devad, regnum, val);
>         } else if (phydev->is_c45) {
>                 u32 addr = MII_ADDR_C45 | (devad << 16) | (regnum & 0xffff);
> --
> 2.17.1
>

Sorry,
-Vladimir