From c8fe62f0768cc9378103fc89fb96804645f527c9 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 4 Mar 2021 13:32:12 -0800 Subject: mptcp: reset 'first' and ack_hint on subflow close Just like with last_snd, we have to NULL 'first' on subflow close. ack_hint isn't strictly required (its never dereferenced), but better to clear this explicitly as well instead of making it an exception. msk->first is dereferenced unconditionally at accept time, but at that point the ssk is not on the conn_list yet -- this means worker can't see it when iterating the conn_list. Reported-by: Paolo Abeni Reviewed-by: Matthieu Baerts Signed-off-by: Florian Westphal Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/protocol.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'net/mptcp/protocol.c') diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index a58da04bed71..3dcb564b03ad 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2169,6 +2169,12 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, if (ssk == msk->last_snd) msk->last_snd = NULL; + if (ssk == msk->ack_hint) + msk->ack_hint = NULL; + + if (ssk == msk->first) + msk->first = NULL; + if (msk->subflow && ssk == msk->subflow->sk) mptcp_dispose_initial_subflow(msk); } @@ -3297,6 +3303,9 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock, /* PM/worker can now acquire the first subflow socket * lock without racing with listener queue cleanup, * we can notify it, if needed. + * + * Even if remote has reset the initial subflow by now + * the refcnt is still at least one. */ subflow = mptcp_subflow_ctx(msk->first); list_add(&subflow->node, &msk->conn_list); -- cgit v1.2.3