[MPTCP] [PATCH] mptcp: reset 'first' and ack_hint on subflow close

[Florian Westphal <fw at strlen.de>]

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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 as well.

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(a)redhat.com>
Signed-off-by: Florian Westphal <fw(a)strlen.de>
---
 net/mptcp/protocol.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index d811f60a867b..acbd2e554ede 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2161,6 +2161,12 @@ 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);
 }
-- 
2.26.2