Subject: Re: [PATCH linux-next 1/4] infiniband/ipoib: fix possible NULL pointer dereference in ipoib_get_iflink

From: Erez Shitrit <[email-masked]>
Date: Wed, 15 Apr 2015 09:17:14 +0300

On 4/14/2015 11:41 PM, Jason Gunthorpe wrote:
> On Tue, Apr 14, 2015 at 07:30:03PM +0300, Erez Shitrit wrote:
>
>>> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
>>> index 657b89b..11ea6e2 100644
>>> +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
>>> @@ -846,7 +846,10 @@ static int ipoib_get_iflink(const struct net_device *dev)
>>>   {
>>>          struct ipoib_dev_priv *priv = netdev_priv(dev);
>>>
>>> -       return priv->parent->ifindex;
>>> +       if (priv && priv->parent)
>>> +               return priv->parent->ifindex;
>>> +       else
>>> +               return 0;
>> This will make parent interface to return 0 instead of its own ifindex.
>> I would suggest write something like that:
> Agree
>
>> +       /* parent interface */
>> +       if (!test_bit(IPOIB_FLAG_SUBINTERFACE, &priv->flags))
>> +               return dev->ifindex;
>> +
>> +       /* child/vlan interface */
>> +       if (!priv->parent)
>> +               return -1;
> Like was said for other drivers, I can't see how parent can be null
> while IPOIB_FLAG_SUBINTERFACE is set. Drop the last if.
It can, at least for ipoib child interface (AKA "vlan"), you can't 
control the call for that ndo and it can be called before the parent was 
set.
> Erez, you basically rewrote this, please make a proper patch with the
> Fixes and Reported-By credit for Honggang. Lets merge this through
> Dave M's tree right away.
>
> Thank you all
>
> Jason
> .
>

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