From nobody Sat Jul 25 07:28:24 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2763D308F23 for ; Wed, 15 Jul 2026 06:05:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.2 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784095561; cv=none; b=hveV8m2E0rwSRy8ll1/+KqRvPb5JcQHXWUXN5BDwpWHOiR44yigt1S3GS2sQ0Fg7OwnB4SZYn0ZMGFnCXJyw0P/7nUTuyWYMJR+Yu735Clk0v3N9aD4RuHGw5O71nSZF1wnMbLHhYTCTmDo2NkV/OsBiv04dC1/4wJGj1zeQ8rI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784095561; c=relaxed/simple; bh=15uX4DlKxDBXMMV0ty2ziRLun/3gN1i+UHxq21jgqN0=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=pN993VeswxLFk1aOgKxdgVRyZyfXuEHv7vcv/YyJQN8RXwaFgEM+LMf3GdO6627ReWh5q9fbDAkJ7RDft5aklCnbMysFk5yStLOJTJGjtHKO37kG0W/LptxYMk6JOshoPyv7bVlnVRke6dhmjhYFrQ89LiAtNvuldSgRTrM7Pmo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=S2ulA/BK; arc=none smtp.client-ip=220.197.31.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="S2ulA/BK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=qH RPdsKA8DAbHGTu/KlfZVpM+L2eBVWtBcRqFCUp/qM=; b=S2ulA/BKKVs8GYD451 IRTaVzII2Il7Mwfk1LMI7fhBROk1VDBoqtf5UhzZ5m2RA5CGHT093KxBNJ2DrgKf h7eRoSngKFucupXEzFnWVttDU+cLzY/YZmkwLvFbAIyhZ2xhQTAGfa8fAIrug1uY xAu89r+Ib+3rA6o+7YsRJ7eKA= Received: from localhost.localdomain (unknown []) by gzga-smtp-mtada-g0-1 (Coremail) with SMTP id _____wD3Xyk+I1dqfHMpJQ--.13861S2; Wed, 15 Jul 2026 14:05:52 +0800 (CST) From: luoqing To: mptcp@lists.linux.dev Subject: [PATCH] mptcp: pm: fix data race in add_addr timer callback Date: Wed, 15 Jul 2026 14:05:50 +0800 Message-Id: <20260715060550.655299-1-l1138897701@163.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wD3Xyk+I1dqfHMpJQ--.13861S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7ZrWrGryDArWUtF18Zw18Krg_yoW5JFW5pF 45Wan5Jr1kJr4Ivr1xAF4DuryjgFZYyryfGw4Y9390yFs5JFyDJay5GF45tFW7JFsYvrn2 yFW0va98Xw4kCaUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07Uo5lnUUUUU= X-CM-SenderInfo: jorrjmiyzxliqr6rljoofrz/xtbC3QBJjWpXI0DhngAA34 Content-Type: text/plain; charset="utf-8" From: luoqing The timer callback reads entry->retrans_times outside pm.lock to decide whether to call mptcp_pm_subflow_established(). Since mptcp_pm_announced_del_timer() can concurrently set retrans_times =3D ADD_ADDR_RETRANS_MAX under pm.lock, a race condition exists. Use a local 'schedule_work' flag set inside pm.lock only when the timer callback itself increments retrans_times to ADD_ADDR_RETRANS_MAX. This ensures that mptcp_pm_subflow_established() is only called when the retransmission naturally exhausts. Additionally, use READ_ONCE/WRITE_ONCE for retrans_times and timer_done to prevent compiler optimizations. Signed-off-by: luoqing --- net/mptcp/pm.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index 6afd39aea110..4c039e7843d3 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -380,6 +380,8 @@ static void mptcp_pm_add_addr_timer(struct timer_list *= timer) struct mptcp_sock *msk =3D entry->sock; struct sock *sk =3D (struct sock *)msk; unsigned int timeout =3D 0; + bool completed =3D false; + u8 retrans_times; =20 pr_debug("msk=3D%p\n", msk); =20 @@ -399,27 +401,33 @@ static void mptcp_pm_add_addr_timer(struct timer_list= *timer) =20 spin_lock_bh(&msk->pm.lock); =20 + retrans_times =3D READ_ONCE(entry->retrans_times); + /* The cancel path (mptcp_pm_announced_del_timer()) can race with this * callback. Once cancel updates retrans_times to MAX, suppress further * retransmissions here. If this callback acquires pm.lock first, one * final transmit attempt is still possible. */ - if (entry->retrans_times < ADD_ADDR_RETRANS_MAX && + if (retrans_times < ADD_ADDR_RETRANS_MAX && !mptcp_pm_should_add_signal_addr(msk)) { pr_debug("retransmit ADD_ADDR id=3D%d\n", entry->addr.id); mptcp_pm_announce_addr(msk, &entry->addr, false); mptcp_pm_add_addr_send_ack(msk); - entry->retrans_times++; + retrans_times++; + WRITE_ONCE(entry->retrans_times, retrans_times); } =20 - if (entry->retrans_times < ADD_ADDR_RETRANS_MAX) + if (retrans_times >=3D ADD_ADDR_RETRANS_MAX) + completed =3D true; + + if (retrans_times < ADD_ADDR_RETRANS_MAX) timeout <<=3D entry->retrans_times; else timeout =3D 0; =20 spin_unlock_bh(&msk->pm.lock); =20 - if (entry->retrans_times =3D=3D ADD_ADDR_RETRANS_MAX) + if (completed) mptcp_pm_subflow_established(msk); =20 out: --=20 2.25.1