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

From: Erez Shitrit <erezsh@dev.mellanox.co.il>
To: Honggang Li <honli@redhat.com>
Cc: Roland Dreier <roland@kernel.org>,
	sean.hefty@intel.com, hal.rosenstock@gmail.com, kaber@trash.net,
	davem@davemloft.net, Alex Estrin <alex.estrin@intel.com>,
	Doug Ledford <dledford@redhat.com>,
	edumazet@google.com, Erez Shitrit <erezsh@mellanox.com>,
	nicolas.dichtel@6wind.com, maheshb@google.com, jbenc@redhat.com,
	ebiederm@xmission.com, elfring@users.sourceforge.net,
	f.fainelli@gmail.com, linux@roeck-us.net, andrew@lunn.ch,
	sfeldma@gmail.com, alexander.h.duyck@intel.com,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH linux-next 1/4] infiniband/ipoib: fix possible NULL pointer dereference in ipoib_get_iflink
Date: Tue, 14 Apr 2015 19:30:03 +0300	[thread overview]
Message-ID: <CAAk-MO-O9sjHQvDfCEuzJJPvUMXJTuRaCzrCkB0xc1DUfK8Aew@mail.gmail.com> (raw)
In-Reply-To: <1429024817-21561-2-git-send-email-honli@redhat.com>

On Tue, Apr 14, 2015 at 6:20 PM, Honggang Li <honli@redhat.com> wrote:
>

[...]

Hi,

> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
> index 657b89b..11ea6e2 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
> +++ 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:

+       /* parent interface */
+       if (!test_bit(IPOIB_FLAG_SUBINTERFACE, &priv->flags))
+               return dev->ifindex;
+
+       /* child/vlan interface */
+       if (!priv->parent)
+               return -1;
+
        return priv->parent->ifindex;

Thanks,
Erez.

>  }
>
>  static u32 ipoib_addr_hash(struct ipoib_neigh_hash *htbl, u8 *daddr)
> --
> 1.8.3.1
>