Re: [PATCH] fix for potential NULL pointer dereference with bare lan743x

[Jakub Kicinski]

On Thu, 29 Oct 2020 03:28:45 +0300 Sergej Bauer wrote:
>   This is just a minor fix which prevents a kernel NULL pointer
> dereference when using phy-less lan743x.
> 
> Signed-off-by: Sergej Bauer 

I take you mean when the device is down netdev->phydev will be NULL?

> diff --git a/drivers/net/ethernet/microchip/lan743x_ethtool.c 
> b/drivers/net/ethernet/microchip/lan743x_ethtool.c
> index dcde496da7fb..354d72d550f2 100644
> --- a/drivers/net/ethernet/microchip/lan743x_ethtool.c
> +++ b/drivers/net/ethernet/microchip/lan743x_ethtool.c
> @@ -793,6 +795,9 @@ static int lan743x_ethtool_set_wol(struct net_device 
> *netdev,
>  {
>   struct lan743x_adapter *adapter = netdev_priv(netdev);
>  
> + if (!netdev->phydev)
> + return -EIO;

Does it make sense to just skip the phy_ethtool_set_wol() call instead?

Also doesn't the wol configuration of the PHY get lost across an
netdev up/down cycle in this driver? Should it be re-applied after phy
is connected back?

>   adapter->wolopts = 0;
>   if (wol->wolopts & WAKE_UCAST)
>   adapter->wolopts |= WAKE_UCAST;

[PATCH] fix for potential NULL pointer dereference with bare lan743x

[Sergej Bauer]

  This is just a minor fix which prevents a kernel NULL pointer
dereference when using phy-less lan743x.

Signed-off-by: Sergej Bauer 
---
 drivers/net/ethernet/microchip/lan743x_ethtool.c | 7 ++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_ethtool.c 
b/drivers/net/ethernet/microchip/lan743x_ethtool.c
index dcde496da7fb..354d72d550f2 100644
--- a/drivers/net/ethernet/microchip/lan743x_ethtool.c
+++ b/drivers/net/ethernet/microchip/lan743x_ethtool.c
@@ -780,7 +780,9 @@ static void lan743x_ethtool_get_wol(struct net_device 
*netdev,
 
wol->supported = 0;
wol->wolopts = 0;
-   phy_ethtool_get_wol(netdev->phydev, wol);
+
+   if (netdev->phydev)
+   phy_ethtool_get_wol(netdev->phydev, wol);
 
wol->supported |= WAKE_BCAST | WAKE_UCAST | WAKE_MCAST |
WAKE_MAGIC | WAKE_PHY | WAKE_ARP;
@@ -793,6 +795,9 @@ static int lan743x_ethtool_set_wol(struct net_device 
*netdev,
 {
struct lan743x_adapter *adapter = netdev_priv(netdev);
 
+   if (!netdev->phydev)
+   return -EIO;
+
adapter->wolopts = 0;
if (wol->wolopts & WAKE_UCAST)
adapter->wolopts |= WAKE_UCAST;
-- 
2.20.1