Hi Hangbin,
On Wed, 6 Feb 2019 20:51:10 +0800
Hangbin Liu <liuhang...@gmail.com> wrote:
> When we add a new GENEVE device with IPv6 remote, checking only for
> IS_ENABLED(CONFIG_IPV6) is not enough as we may disable IPv6 in kernel
> cmd(ipv6.disable=1), which will cause a NULL pointer dereference.
>
> Reported-by: Jianlin Shi <ji...@redhat.com>
> Signed-off-by: Hangbin Liu <liuhang...@gmail.com>
> ---
> drivers/net/geneve.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
> index 58bbba8582b0..0658715581e3 100644
> --- a/drivers/net/geneve.c
> +++ b/drivers/net/geneve.c
> @@ -1512,6 +1512,10 @@ static void geneve_link_config(struct net_device *dev,
> }
> #if IS_ENABLED(CONFIG_IPV6)
> case AF_INET6: {
> + struct inet6_dev *idev = in6_dev_get(dev);
> + if (!idev)
> + break;
> +
> struct rt6_info *rt = rt6_lookup(geneve->net,
> &info->key.u.ipv6.dst, NULL, 0,
> NULL, 0);
You're mixing declarations and code here, ISO C90 forbids it. You
could rather declare:
struct inet6_dev *idev = in6_dev_get(dev);
struct rt6_info *rt;
then check idev, and then call rt6_lookup().
> @@ -1519,6 +1523,8 @@ static void geneve_link_config(struct net_device *dev,
> if (rt && rt->dst.dev)
> ldev_mtu = rt->dst.dev->mtu - GENEVE_IPV6_HLEN;
> ip6_rt_put(rt);
> +
> + in6_dev_put(idev);
I think it would be better to put this right after the check on idev,
mostly for readability, but also, marginally, to reduce the scope of
the reference count bump.
--
Stefano
