netdev - Re: [PATCH net] wireguard: fix use-after-free in root_remove_peer

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Date:   Mon, 3 Feb 2020 10:17:57 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "Jason A. Donenfeld" <Jason@...c4.com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        syzbot <syzkaller@...glegroups.com>,
        WireGuard mailing list <wireguard@...ts.zx2c4.com>
Subject: Re: [PATCH net] wireguard: fix use-after-free in
 root_remove_peer_lists



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@...gle.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 :)