[PATCH net] wireguard: fix use-after-free in root_remove_peer_lists

[Eric Dumazet]

On 2/3/20 9:29 AM, Jason A. Donenfeld wrote:
> Hi Eric,
> 
> On Mon, Feb 3, 2020 at 6:19 PM Eric Dumazet <edumazet at google.com> wrote:
>> diff --git a/drivers/net/wireguard/allowedips.c b/drivers/net/wireguard/allowedips.c
>> index 121d9ea0f13584f801ab895753e936c0a12f0028..3725e9cd85f4f2797afd59f42af454acc107aa9a 100644
>> --- a/drivers/net/wireguard/allowedips.c
>> +++ b/drivers/net/wireguard/allowedips.c
>> @@ -263,6 +263,7 @@ static int add(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
>>         } else {
>>                 node = kzalloc(sizeof(*node), GFP_KERNEL);
>>                 if (unlikely(!node)) {
>> +                       list_del(&newnode->peer_list);
>>                         kfree(newnode);
>>                         return -ENOMEM;
>>                 }
>> --
>> 2.25.0.341.g760bfbb309-goog
> 
> Thanks, nice catch. I remember switching that code over to using the
> peer_list somewhat recently and embarrassed I missed this. Glad to see
> WireGuard is hooked up to syzkaller.
> 

I will let you work on a lockdep issue that syzbot found :)