[PATCH net 5/9] mptcp: reset 'first' and ack_hint on subflow close
From: Mat Martineau <hidden>
Date: 2021-03-04 21:36:05
Also in:
mptcp
Subsystem:
networking [general], networking [mptcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Matthieu Baerts, Mat Martineau, Linus Torvalds
From: Florian Westphal <fw@strlen.de> 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 <pabeni@redhat.com> Reviewed-by: Matthieu Baerts <redacted> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Mat Martineau <redacted> --- net/mptcp/protocol.c | 9 +++++++++ 1 file changed, 9 insertions(+)
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);
--
2.30.1