This is a note to let you know that I've just added the patch titled
mptcp: process pending subflow error on close
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mptcp-process-pending-subflow-error-on-close.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 25532afde428aef9d85923b345150355c5ff2c0e
Author: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Sat Sep 16 12:52:47 2023 +0200
mptcp: process pending subflow error on close
[ Upstream commit 9f1a98813b4b686482e5ef3c9d998581cace0ba6 ]
On incoming TCP reset, subflow closing could happen before error
propagation. That in turn could cause the socket error being ignored,
and a missing socket state transition, as reported by Daire-Byrne.
Address the issues explicitly checking for subflow socket error at
close time. To avoid code duplication, factor-out of __mptcp_error_report()
a new helper implementing the relevant bits.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/429
Fixes: 15cc10453398 ("mptcp: deliver ssk errors to msk")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 193f2bdc8fe1b..b6e0579e72644 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -765,40 +765,44 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
return moved;
}
-void __mptcp_error_report(struct sock *sk)
+static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)
{
- struct mptcp_subflow_context *subflow;
- struct mptcp_sock *msk = mptcp_sk(sk);
+ int err = sock_error(ssk);
+ int ssk_state;
- mptcp_for_each_subflow(msk, subflow) {
- struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
- int err = sock_error(ssk);
- int ssk_state;
+ if (!err)
+ return false;
- if (!err)
- continue;
+ /* only propagate errors on fallen-back sockets or
+ * on MPC connect
+ */
+ if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk)))
+ return false;
- /* only propagate errors on fallen-back sockets or
- * on MPC connect
- */
- if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
- continue;
+ /* We need to propagate only transition to CLOSE state.
+ * Orphaned socket will see such state change via
+ * subflow_sched_work_if_closed() and that path will properly
+ * destroy the msk as needed.
+ */
+ ssk_state = inet_sk_state_load(ssk);
+ if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
+ inet_sk_state_store(sk, ssk_state);
+ WRITE_ONCE(sk->sk_err, -err);
- /* We need to propagate only transition to CLOSE state.
- * Orphaned socket will see such state change via
- * subflow_sched_work_if_closed() and that path will properly
- * destroy the msk as needed.
- */
- ssk_state = inet_sk_state_load(ssk);
- if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
- inet_sk_state_store(sk, ssk_state);
- WRITE_ONCE(sk->sk_err, -err);
-
- /* This barrier is coupled with smp_rmb() in mptcp_poll() */
- smp_wmb();
- sk_error_report(sk);
- break;
- }
+ /* This barrier is coupled with smp_rmb() in mptcp_poll() */
+ smp_wmb();
+ sk_error_report(sk);
+ return true;
+}
+
+void __mptcp_error_report(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow;
+ struct mptcp_sock *msk = mptcp_sk(sk);
+
+ mptcp_for_each_subflow(msk, subflow)
+ if (__mptcp_subflow_error_report(sk, mptcp_subflow_tcp_sock(subflow)))
+ break;
}
/* In most cases we will be able to lock the mptcp socket. If its already
@@ -2446,6 +2450,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
}
out_release:
+ __mptcp_subflow_error_report(sk, ssk);
release_sock(ssk);
sock_put(ssk);
