Re: [PATCH] net: Fix potential memory leak in proto_register()

[David Miller]

From: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Date: Tue, 11 Aug 2020 16:02:51 -0700

>> @@ -3406,6 +3406,16 @@ static void sock_inuse_add(struct net *net, int val)
>>  }
>>  #endif
>>
>> +static void tw_prot_cleanup(struct timewait_sock_ops *twsk_prot)
>> +{
>> +       if (!twsk_prot)
>> +               return;
>> +       kfree(twsk_prot->twsk_slab_name);
>> +       twsk_prot->twsk_slab_name = NULL;
>> +       kmem_cache_destroy(twsk_prot->twsk_slab);
> 
> Hmm, are you sure you can free the kmem cache name before
> kmem_cache_destroy()? To me, it seems kmem_cache_destroy()
> frees the name via slab_kmem_cache_release() via kfree_const().
> With your patch, we have a double-free on the name?
> 
> Or am I missing anything?

Yep, there is a double free here.

Please fix this.