This is a note to let you know that I've just added the patch titled mptcp: be careful on subflow status propagation on errors 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-be-careful-on-subflow-status-propagation-on-errors.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. >From 1249db44a102d9d3541ed7798d4b01ffdcf03524 Mon Sep 17 00:00:00 2001 From: Paolo Abeni <pabeni@xxxxxxxxxx> Date: Tue, 7 Feb 2023 14:04:16 +0100 Subject: mptcp: be careful on subflow status propagation on errors From: Paolo Abeni <pabeni@xxxxxxxxxx> commit 1249db44a102d9d3541ed7798d4b01ffdcf03524 upstream. Currently the subflow error report callback unconditionally propagates the fallback subflow status to the owning msk. If the msk is already orphaned, the above prevents the code from correctly tracking the msk moving to the TCP_CLOSE state and doing the appropriate cleanup. All the above causes increasing memory usage over time and sporadic self-tests failures. There is a great deal of infrastructure trying to propagate correctly the fallback subflow status to the owning mptcp socket, e.g. via mptcp_subflow_eof() and subflow_sched_work_if_closed(): in the error propagation path we need only to cope with unorphaned sockets. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/339 Fixes: 15cc10453398 ("mptcp: deliver ssk errors to msk") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> Reviewed-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx> Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/mptcp/subflow.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1344,6 +1344,7 @@ void __mptcp_error_report(struct sock *s mptcp_for_each_subflow(msk, subflow) { struct sock *ssk = mptcp_subflow_tcp_sock(subflow); int err = sock_error(ssk); + int ssk_state; if (!err) continue; @@ -1354,7 +1355,14 @@ void __mptcp_error_report(struct sock *s if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk)) continue; - inet_sk_state_store(sk, inet_sk_state_load(ssk)); + /* 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); sk->sk_err = -err; /* This barrier is coupled with smp_rmb() in mptcp_poll() */ Patches currently in stable-queue which might be from pabeni@xxxxxxxxxx are queue-6.1/selftests-forwarding-lib-quote-the-sysctl-values.patch queue-6.1/mptcp-be-careful-on-subflow-status-propagation-on-errors.patch queue-6.1/selftests-mptcp-allow-more-slack-for-slow-test-case.patch queue-6.1/net-mscc-ocelot-fix-vcap-filters-not-matching-on-mac.patch queue-6.1/mptcp-do-not-wait-for-bare-sockets-timeout.patch queue-6.1/net-mscc-ocelot-fix-all-ipv6-getting-trapped-to-cpu-.patch queue-6.1/hv_netvsc-allocate-memory-in-netvsc_dma_map-with-gfp_atomic.patch queue-6.1/rds-rds_rm_zerocopy_callback-use-list_first_entry.patch queue-6.1/net-dsa-mt7530-don-t-change-pvc_eg_tag-when-cpu-port.patch