Re: [PATCH bpf v2] net: bpf: don't leak time wait and request sockets

[Alexei Starovoitov]

On Fri, Jan 10, 2020 at 8:43 AM Martin Lau <kafai@xxxxxx> wrote:
>
> On Fri, Jan 10, 2020 at 01:23:36PM +0000, Lorenz Bauer wrote:
> > It's possible to leak time wait and request sockets via the following
> > BPF pseudo code:
> >
> >   sk = bpf_skc_lookup_tcp(...)
> >   if (sk)
> >     bpf_sk_release(sk)
> >
> > If sk->sk_state is TCP_NEW_SYN_RECV or TCP_TIME_WAIT the refcount taken
> > by bpf_skc_lookup_tcp is not undone by bpf_sk_release. This is because
> > sk_flags is re-used for other data in both kinds of sockets. The check
> >
> >   !sock_flag(sk, SOCK_RCU_FREE)
> >
> > therefore returns a bogus result. Check that sk_flags is valid by calling
> > sk_fullsock. Skip checking SOCK_RCU_FREE if we already know that sk is
> > not a full socket.
> Acked-by: Martin KaFai Lau <kafai@xxxxxx>

Applied. Thanks