On 02/06/2019 10:54 AM, David Ahern wrote:
> On 2/6/19 4:51 AM, Hangbin Liu 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 <[email protected]>
>> Signed-off-by: Hangbin Liu <[email protected]>
>> ---
>> 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;
>
> Since you don't need an idev reference rcu_access_pointer should be
> enough to say v6 is enabled on this device. ie., add a helper to check
> that rcu_access_pointer(dev->ip6_ptr) is non-NULL
>
I guess RTNL is held at this point, so we can use a lockdep enabled
accessor : __in6_dev_get()
