The patch below does not apply to the 6.7-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.7.y git checkout FETCH_HEAD git cherry-pick -x 3f83d8a77eeeb47011b990fd766a421ee64f1d73 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024021909-wobbling-taste-4260@gregkh' --subject-prefix 'PATCH 6.7.y' HEAD^..

Possible dependencies:

3f83d8a77eee ("mptcp: fix more tx path fields initialization") 013e3179dbd2 ("mptcp: fix rcv space initialization") c693a8516429 ("mptcp: use mptcp_set_state")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3f83d8a77eeeb47011b990fd766a421ee64f1d73 Mon Sep 17 00:00:00 2001 From: Paolo Abeni pabeni@redhat.com Date: Thu, 8 Feb 2024 19:03:51 +0100 Subject: [PATCH] mptcp: fix more tx path fields initialization

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

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7632eafb683b..8cb6a873dae9 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3478,10 +3478,8 @@ 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 56b2ac2f2f22..c2df34ebcf28 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); }