[PATCH 6.6 122/299] mptcp: fix more tx path fields initialization

Greg Kroah-Hartman
2024-02-27T13:54:06Z

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 3f83d8a77eeeb47011b990fd766a421ee64f1d73 ]

The 'msk->write_seq' and 'msk->snd_nxt' are always updated under
the msk socket lock, except at MPC handshake completiont time.

Builds-up on the previous commit to move such init under the relevant
lock.

There are no known problems caused by the potential race, the
primary goal is consistency.

Fixes: 6d0060f600ad ("mptcp: Write MPTCP DSS headers to outgoing data packets")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: e4a0fa47e816 ("mptcp: corner case locking for rx path fields initialization")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/mptcp/protocol.c | 6 ++----
net/mptcp/subflow.c | 13 +++++++++++--
2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 2f794924ae5d4..55a90a7b7b517 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3525,10 +3525,8 @@ void mptcp_finish_connect(struct sock *ssk)
* accessing the field below
*/
WRITE_ONCE(msk->local_key, subflow->local_key);
- WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
- WRITE_ONCE(msk->snd_nxt, msk->write_seq);
- WRITE_ONCE(msk->snd_una, msk->write_seq);
- WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
+ WRITE_ONCE(msk->snd_una, subflow->idsn + 1);
+ WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd);

mptcp_pm_new_connection(msk, ssk, 0);
}
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 15f456fb28977..ba739e7009221 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -421,12 +421,21 @@ static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct soc

void __mptcp_sync_state(struct sock *sk, int state)
{
+ struct mptcp_subflow_context *subflow;
struct mptcp_sock *msk = mptcp_sk(sk);
+ struct sock *ssk = msk->first;

- __mptcp_propagate_sndbuf(sk, msk->first);
+ subflow = mptcp_subflow_ctx(ssk);
+ __mptcp_propagate_sndbuf(sk, ssk);
if (!msk->rcvspace_init)
- mptcp_rcv_space_init(msk, msk->first);
+ mptcp_rcv_space_init(msk, ssk);
+
if (sk->sk_state == TCP_SYN_SENT) {
+ /* subflow->idsn is always available is TCP_SYN_SENT state,
+ * even for the FASTOPEN scenarios
+ */
+ WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
+ WRITE_ONCE(msk->snd_nxt, msk->write_seq);
mptcp_set_state(sk, state);
sk->sk_state_change(sk);
}
--
2.43.0