kernel/linux.git/net/mptcp, branch v7.1-rc5

mptcp: update window_clamp on subflows when SO_RCVBUF is set

2026-05-19T13:36:35+00:00

Add __mptcp_subflow_set_rcvbuf() helper to write the subflow sk_rcvbuf, but also to call the recently added tcp_set_rcvbuf() helper to update window_clamp. This is needed because the window clap is updated when scaling_ratio changes, in tcp_measure_rcv_mss(). Until scaling_ratio changes, the subflow is stuck with the old window clamp which may be based on a small initial buffer. Use this new helper in both mptcp_sol_socket_sync_intval() (setsockopt path) and sync_socket_options() (new subflow creation path). Note that this patch depends on commit b025461303d8 ("tcp: update window_clamp when SO_RCVBUF is set"): it fixes the issue on TCP side, but the same fix is needed on MPTCP side as well. Fixes: a2cbb1603943 ("tcp: Update window clamping condition") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/619 Signed-off-by: Gang Yan Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-5-701e96419f2f@kernel.org Signed-off-by: Paolo Abeni

mptcp: reset rcv wnd on disconnect

2026-05-19T13:36:35+00:00

If the MPTCP socket fallback to TCP before the MP handshake completion, the IASN remain 0, and the rcv_wnd_sent field is not explicitly initialized, just incremented over time with the data transfer. At disconnect time such value is not cleared. If the next connection falls back to TCP before the MP handshake completion, the data transfer will keep incrementing the receive window end sequence starting from the last value used in the previous connection: the announced window will be unrelated from the actual receiver buffer size and likely too big. Address the issue zeroing the field at disconnect time. Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-4-701e96419f2f@kernel.org Signed-off-by: Paolo Abeni

mptcp: pm: fix ADD_ADDR timer infinite retry on option space insufficient

2026-05-19T13:36:35+00:00

When TCP option space is insufficient (e.g., when sending ADD_ADDR with an IPv6 address and port while tcp_timestamps is enabled), the original code jumped to out_unlock without clearing the addr_signal flag. This caused mptcp_pm_add_timer to keep rescheduling indefinitely, not sending ADD_ADDR, preventing subsequent addresses in the endpoint list from being announced. Handle this case by clearing the ADD_ADDR signal and skipping the matching ADD_ADDR retransmission entry. The skip path cancels the matching timer (with id check) and advances PM state progression, preserving forward progress to subsequent PM work. This cancellation is inherently best-effort. A concurrent add_timer callback may already be running and may acquire pm.lock before the cancel path updates entry state. In that case, one final ADD_ADDR transmit attempt can still be executed. Once the cancel path sets entry->retrans_times to ADD_ADDR_RETRANS_MAX, the callback-side retrans_times check suppresses further ADD_ADDR retransmissions. Note that when an ADD_ADDR is being prepared, a pure-ACK is queued. On the output side, it means that it is fine to skip non-pure-ACK packets, when drop_other_suboptions is set: a pure-ACK will be processed soon after. Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout") Cc: stable@vger.kernel.org Signed-off-by: Li Xiasong Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-2-701e96419f2f@kernel.org Signed-off-by: Paolo Abeni

mptcp: do not drop partial packets

2026-05-19T13:36:35+00:00

When a packet arrives with map_seq < ack_seq < end_seq, the beginning of the packet has already been acknowledged but the end contains new data. Currently the entire packet is dropped as "old data," forcing the sender to retransmit. Instead, skip the already-acked bytes by adjusting the skb offset and enqueue only the new portion. Update bytes_received and ack_seq to reflect the new data consumed. A previous attempt at this fix has been sent by Paolo Abeni [1], but had issues [2]: it also added a zero-window check and changed rcv_wnd_sent initialization, which caused test regressions. This version addresses only the partial packet handling without modifying receive window accounting. Fixes: ab174ad8ef76 ("mptcp: move ooo skbs into msk out of order queue.") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/c9b426a4e163aa3c4fe8b80c79f1a610f47ae7d8.1763075056.git.pabeni@redhat.com [1] Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/600 [2] Signed-off-by: Shardul Bankar [pabeni@redhat.com: update map] Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-1-701e96419f2f@kernel.org Signed-off-by: Paolo Abeni

Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2026-05-10T01:42:54+00:00

Pull bpf fixes from Alexei Starovoitov: - Fix sk_local_storage diag dump via netlink (Amery Hung) - Fix off-by-one in arena direct-value access (Junyoung Jang) - Reject TCP_NODELAY in bpf-tcp congestion control (KaFai Wan) - Fix type confusion in bpf_*_sock() (Kuniyuki Iwashima) - Reject TX-only AF_XDP sockets (Linpu Yu) - Don't run arg-tracking analysis twice on main subprog (Paul Chaignon) - Fix NULL pointer dereference in bpf_sk_storage_clone and fib lookup (Weiming Shi) * tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: bpf: Fix off-by-one boundary validation in arena direct-value access xskmap: reject TX-only AF_XDP sockets bpf: Don't run arg-tracking analysis twice on main subprog bpf: Free reuseport cBPF prog after RCU grace period. bpf: tcp: Fix type confusion in sol_tcp_sockopt(). bpf: tcp: Fix type confusion in bpf_skc_to_tcp6_sock(). bpf: tcp: Fix type confusion in bpf_skc_to_tcp_sock(). mptcp: bpf: Fix type confusion in bpf_mptcp_sock_from_subflow() selftest: bpf: Add test for bpf_tcp_sock() and RAW socket. bpf: tcp: Fix type confusion in bpf_tcp_sock(). tools/headers: Regenerate stddef.h to fix BPF selftests bpf: Fix sk_local_storage diag dumping uninitialized special fields bpf: Fix NULL pointer dereference in bpf_skb_fib_lookup() sockmap: Fix sk_psock_drop() race vs sock_map_{unhash,close,destroy}(). bpf: Fix NULL pointer dereference in bpf_sk_storage_clone and diag paths selftests/bpf: Verify bpf-tcp-cc rejects TCP_NODELAY selftests/bpf: Test TCP_NODELAY in TCP hdr opt callbacks bpf: Reject TCP_NODELAY in bpf-tcp-cc bpf: Reject TCP_NODELAY in TCP header option callbacks

mptcp: bpf: Fix type confusion in bpf_mptcp_sock_from_subflow()

2026-05-08T18:38:10+00:00

bpf_mptcp_sock_from_subflow() only checks if sk->sk_protocol is IPPROTO_TCP, but RAW socket can bypass it: socket(AF_INET, SOCK_RAW, IPPROTO_TCP) In this case, it would NOT be valid to call sk_is_mptcp() which will assume sk is a pointer to a struct tcp_sock, and wrongly checks for: tcp_sk(sk)->is_mptcp. Fixes: 3bc253c2e652 ("bpf: Add bpf_skc_to_mptcp_sock_proto") Signed-off-by: Matthieu Baerts (NGI0) Signed-off-by: Kuniyuki Iwashima Signed-off-by: Martin KaFai Lau Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260504210610.180150-4-kuniyu@google.com

mptcp: pm: prio: skip closed subflows

2026-05-07T01:16:45+00:00

When sending an MP_PRIO, closed subflows need to be skipped. This fixes the case where the initial subflow got closed, re-opened later, then an MP_PRIO is needed for the same local address. Note that explicit MP_PRIO cannot be sent during the 3WHS, so it is fine to use __mptcp_subflow_active(). Fixes: 067065422fcd ("mptcp: add the outgoing MP_PRIO support") Cc: stable@vger.kernel.org Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260505-net-mptcp-pm-fixes-7-1-rc3-v1-9-fca8091060a4@kernel.org Signed-off-by: Jakub Kicinski

mptcp: pm: ADD_ADDR rtx: return early if no retrans

2026-05-07T01:16:45+00:00

No need to iterate over all subflows if there is no retransmission needed. Exit early in this case then. Fixes: 30549eebc4d8 ("mptcp: make ADD_ADDR retransmission timeout adaptive") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260505-net-mptcp-pm-fixes-7-1-rc3-v1-8-fca8091060a4@kernel.org Signed-off-by: Jakub Kicinski

mptcp: pm: ADD_ADDR rtx: skip inactive subflows

2026-05-07T01:16:45+00:00

When looking at the maximum RTO amongst the subflows, inactive subflows were taken into account: that includes stale ones, and the initial one if it has been already been closed. Unusable subflows are now simply skipped. Stale ones are used as an alternative: if there are only stale ones, to take their maximum RTO and avoid to eventually fallback to net.mptcp.add_addr_timeout, which is set to 2 minutes by default. Fixes: 30549eebc4d8 ("mptcp: make ADD_ADDR retransmission timeout adaptive") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260505-net-mptcp-pm-fixes-7-1-rc3-v1-7-fca8091060a4@kernel.org Signed-off-by: Jakub Kicinski

mptcp: pm: ADD_ADDR rtx: resched blocked ADD_ADDR quicker

2026-05-07T01:16:45+00:00

When an ADD_ADDR needs to be retransmitted and another one has already been prepared -- e.g. multiple ADD_ADDRs have been sent in a row and need to be retransmitted later -- this additional retransmission will need to wait. In this case, the timer was reset to TCP_RTO_MAX / 8, which is ~15 seconds. This delay is unnecessary long: it should just be rescheduled at the next opportunity, e.g. after the retransmission timeout. Without this modification, some issues can be seen from time to time in the selftests when multiple ADD_ADDRs are sent, and the host takes time to process them, e.g. the "signal addresses, ADD_ADDR timeout" MPTCP Join selftest, especially with a debug kernel config. Note that on older kernels, 'timeout' is not available. It should be enough to replace it by one second (HZ). Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260505-net-mptcp-pm-fixes-7-1-rc3-v1-6-fca8091060a4@kernel.org Signed-off-by: Jakub Kicinski