[PATCH net] net: phy: don't allow __set_phy_supported to add unsupported modes

[PATCH net] net: phy: don't allow __set_phy_supported to add unsupported modes

[Heiner Kallweit]

Currently __set_phy_supported allows to add modes w/o checking whether
the PHY supports them. This is wrong, it should never add modes but
only remove modes we don't want to support.

The commit marked as fixed didn't do anything wrong, it just copied
existing functionality to the helper which is being fixed now.

Fixes: f3a6bd393c2c ("phylib: Add phy_set_max_speed helper")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
This will cause a merge conflict once net is merged into net-next.
And the fix will need minor tweaking when being backported to
older kernel versions.
---
 drivers/net/phy/phy_device.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 23ee3967c..18e92c19c 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1880,20 +1880,17 @@ EXPORT_SYMBOL(genphy_loopback);
 
 static int __set_phy_supported(struct phy_device *phydev, u32 max_speed)
 {
-	phydev->supported &= ~(PHY_1000BT_FEATURES | PHY_100BT_FEATURES |
-			       PHY_10BT_FEATURES);
-
 	switch (max_speed) {
-	default:
-		return -ENOTSUPP;
-	case SPEED_1000:
-		phydev->supported |= PHY_1000BT_FEATURES;
+	case SPEED_10:
+		phydev->supported &= ~PHY_100BT_FEATURES;
 		/* fall through */
 	case SPEED_100:
-		phydev->supported |= PHY_100BT_FEATURES;
-		/* fall through */
-	case SPEED_10:
-		phydev->supported |= PHY_10BT_FEATURES;
+		phydev->supported &= ~PHY_1000BT_FEATURES;
+		break;
+	case SPEED_1000:
+		break;
+	default:
+		return -ENOTSUPP;
 	}
 
 	return 0;
-- 
2.19.2

Re: [PATCH net] net: phy: don't allow __set_phy_supported to add unsupported modes

[Andrew Lunn]

On Mon, Dec 03, 2018 at 08:19:33AM +0100, Heiner Kallweit wrote:
> Currently __set_phy_supported allows to add modes w/o checking whether
> the PHY supports them. This is wrong, it should never add modes but
> only remove modes we don't want to support.
> 
> The commit marked as fixed didn't do anything wrong, it just copied
> existing functionality to the helper which is being fixed now.
> 
> Fixes: f3a6bd393c2c ("phylib: Add phy_set_max_speed helper")
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH net] net: phy: don't allow __set_phy_supported to add unsupported modes

[David Miller]

From: Heiner Kallweit <hkallweit1@gmail.com>
Date: Mon, 3 Dec 2018 08:19:33 +0100

> Currently __set_phy_supported allows to add modes w/o checking whether
> the PHY supports them. This is wrong, it should never add modes but
> only remove modes we don't want to support.
> 
> The commit marked as fixed didn't do anything wrong, it just copied
> existing functionality to the helper which is being fixed now.
> 
> Fixes: f3a6bd393c2c ("phylib: Add phy_set_max_speed helper")
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> This will cause a merge conflict once net is merged into net-next.
> And the fix will need minor tweaking when being backported to
> older kernel versions.

Applied and queued up for -stable.

I'll let you know if I need help with those backports.