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 <[email protected]> Tested-by: Christoph Paasch <[email protected]> Signed-off-by: Paolo Abeni <[email protected]> --- net/mptcp/subflow.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 7f3ef1840df5..3ef445f59556 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -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; -- 2.26.2
