[Devel] [PATCH 1/2] netns: fix NULL-dereference in dev_net()

[Brian Haley]

Alexey Dobriyan wrote:
> On Thu, Aug 14, 2008 at 03:27:25PM -0400, Brian Haley wrote:
>> Change dev_net() to handle a NULL argument - return &init_net instead.
> 
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -781,10 +781,10 @@ static inline
>>  struct net *dev_net(const struct net_device *dev)
>>  {
>>  #ifdef CONFIG_NET_NS
>> -	return dev->nd_net;
>> -#else
>> -	return &init_net;
>> +	if (dev)
>> +		return dev->nd_net;
>>  #endif
>> +	return &init_net;
>>  }
> 
> This is ugly and wrong.
> 
> The only assymetry between init_net and dynamically created netns is
> that some data structures are created only when init_net is initialized
> like some kmem caches and so on.
> 
> And some sysctls that some people may ban in netns.
> 
> Modulo that, init_net is no different from the rest.

So would you rather have all the callers that aren't net-namespace aware 
pass &init_net?  That seemed like a worse solution to me.

-Brian