From 5cd6e0ad79d2615264f63929f8b457ad97ae550d Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" Date: Tue, 5 May 2026 17:00:51 +0200 Subject: [PATCH] mptcp: pm: ADD_ADDR rtx: fix potential data-race This mptcp_pm_add_timer() helper is executed as a timer callback in softirq context. To avoid any data races, the socket lock needs to be held with bh_lock_sock(). If the socket is in use, retry again soon after, similar to what is done with the keepalive timer. 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-v1-3-fca8091060a4@kernel.org Signed-off-by: Jakub Kicinski --- net/mptcp/pm.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index 5056eb8db24e..3912128d9b86 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -337,6 +337,13 @@ static void mptcp_pm_add_timer(struct timer_list *timer) if (inet_sk_state_load(sk) == TCP_CLOSE) return; + bh_lock_sock(sk); + if (sock_owned_by_user(sk)) { + /* Try again later. */ + sk_reset_timer(sk, timer, jiffies + HZ / 20); + goto out; + } + if (mptcp_pm_should_add_signal_addr(msk)) { sk_reset_timer(sk, timer, jiffies + TCP_RTO_MAX / 8); goto out; @@ -365,6 +372,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer) mptcp_pm_subflow_established(msk); out: + bh_unlock_sock(sk); __sock_put(sk); } -- 2.30.2