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

[Jason A. Donenfeld]

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've queued this up in my stable tree, and I'll send this back out in
a few days:
https://git.zx2c4.com/wireguard-linux/commit/?h=stable&id=3492daa8815770038c9da36382dc66cea76ad4fc

Jason