subflow: explicitly check for plain tcp rsk

When syncookie are in use, the TCP stack may feed into
subflow_syn_recv_sock() plain TCP request sockets. We can't
access mptcp_subflow_request_sock-specific fields on such
sockets. Explicitly check the rsk ops to do safe accesses.

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2020-07-23 13:02:34 +02:00 committed by David S. Miller
parent fa25e815d9
commit b7514694ed

View File

@ -415,7 +415,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
/* hopefully temporary handling for MP_JOIN+syncookie */
subflow_req = mptcp_subflow_rsk(req);
fallback_is_fatal = subflow_req->mp_join;
fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
fallback = !tcp_rsk(req)->is_mptcp;
if (fallback)
goto create_child;