From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C371D347FE6; Tue, 17 Feb 2026 12:33:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771331630; cv=none; b=tgIS+XBMUSyJdVQsFQDWSayXqgjMyOB3rymI4MlthjKeJ3BTV23oIGtbOdqdnUwMvwgVvgLWHICC8bgRyMgoWvsxZ7UdFNNxw1vGmZabp56MxRPwdLG3MuglGLDClqRLZaIdCoMIwVkFYhZ4pHqOxlm9xcKn3Kx2lMrcVkVLSAg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771331630; c=relaxed/simple; bh=mmmuNYnHvf2LCc3AFd1I2DzH+ExHY11c5oCmwtxcCrI=; h=Subject:To:Cc:From:Date:In-Reply-To:Message-ID:MIME-Version: Content-Type; b=VZ1IUB6xoInZmvDS5DWHTi+5PJlNn46NJl0piA6Hx/+dUBYofN6JS7QkvOUbLWz9Z/ztKo8Wx7H2R7N0ytUfbimBjqpZqLtCe/u2Fk8Lwtzt3IR5SPMcjshVejkBAMB3bpDCvKzQjRBHwkpnjgXRiCZgABKVFhDWqcu46gZyF98= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CWeTU7Tc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CWeTU7Tc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15351C4CEF7; Tue, 17 Feb 2026 12:33:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1771331630; bh=mmmuNYnHvf2LCc3AFd1I2DzH+ExHY11c5oCmwtxcCrI=; h=Subject:To:Cc:From:Date:In-Reply-To:From; b=CWeTU7TcpM53StWjP6hVSlkcT3g5WhBD0QcpJaYETi0lT/FMck5M37cIuNcUStH+v wIWIQcaqRiu1j1eE2DWoGfFzIZxDluEokNflxGeGZVMITCkXMoBUq4zJ5cEyBXLnLj OC+VTkUYRKAd6XBgu6Od+CTfsVo2Ahn1NK7jGcP4= Subject: Patch "mptcp: fix race in mptcp_pm_nl_flush_addrs_doit()" has been added to the 6.1-stable tree To: edumazet@google.com,eulgyukim@snu.ac.kr,gregkh@linuxfoundation.org,kuba@kernel.org,martineau@kernel.org,matttbe@kernel.org,mptcp@lists.linux.dev,syzbot+5498a510ff9de39d37da@syzkaller.appspotmail.com Cc: From: Date: Tue, 17 Feb 2026 13:33:39 +0100 In-Reply-To: <20260212174051.1839592-2-matttbe@kernel.org> Message-ID: <2026021739-spinal-tree-c8cf@gregkh> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit X-stable: commit X-Patchwork-Hint: ignore This is a note to let you know that I've just added the patch titled mptcp: fix race in mptcp_pm_nl_flush_addrs_doit() 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-fix-race-in-mptcp_pm_nl_flush_addrs_doit.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 know about it. >From stable+bounces-215983-greg=kroah.com@vger.kernel.org Thu Feb 12 18:41:08 2026 From: "Matthieu Baerts (NGI0)" Date: Thu, 12 Feb 2026 18:40:52 +0100 Subject: mptcp: fix race in mptcp_pm_nl_flush_addrs_doit() To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: MPTCP Upstream , Eric Dumazet , syzbot+5498a510ff9de39d37da@syzkaller.appspotmail.com, Eulgyu Kim , Mat Martineau , "Matthieu Baerts (NGI0)" , Jakub Kicinski Message-ID: <20260212174051.1839592-2-matttbe@kernel.org> From: Eric Dumazet commit e2a9eeb69f7d4ca4cf4c70463af77664fdb6ab1d upstream. syzbot and Eulgyu Kim reported crashes in mptcp_pm_nl_get_local_id() and/or mptcp_pm_nl_is_backup() Root cause is list_splice_init() in mptcp_pm_nl_flush_addrs_doit() which is not RCU ready. list_splice_init_rcu() can not be called here while holding pernet->lock spinlock. Many thanks to Eulgyu Kim for providing a repro and testing our patches. Fixes: 141694df6573 ("mptcp: remove address when netlink flushes addrs") Signed-off-by: Eric Dumazet Reported-by: syzbot+5498a510ff9de39d37da@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6970a46d.a00a0220.3ad28e.5cf0.GAE@google.com/T/ Reported-by: Eulgyu Kim Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/611 Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260124-net-mptcp-race_nl_flush_addrs-v3-1-b2dc1b613e9d@kernel.org Signed-off-by: Jakub Kicinski [ Conflicts because the code has been moved from pm_netlink.c to pm_kernel.c later on in commit 8617e85e04bd ("mptcp: pm: split in-kernel PM specific code"). The same modifications can be applied in pm_netlink.c with one exception, because 'pernet->local_addr_list' has been renamed to 'pernet->endp_list' in commit 35e71e43a56d ("mptcp: pm: in-kernel: rename 'local_addr_list' to 'endp_list'"). The previous name is then still being used in this version. Also, another conflict is caused by commit 7bcf4d8022f9 ("mptcp: pm: rename helpers linked to 'flush'") which is not in this version: mptcp_nl_remove_addrs_list() has been renamed to mptcp_nl_flush_addrs_list(). The previous name has then been kept. ] Signed-off-by: Matthieu Baerts (NGI0) Signed-off-by: Greg Kroah-Hartman --- net/mptcp/pm_netlink.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -1855,16 +1855,26 @@ static void __reset_counters(struct pm_n static int mptcp_nl_cmd_flush_addrs(struct sk_buff *skb, struct genl_info *info) { struct pm_nl_pernet *pernet = genl_info_pm_nl(info); - LIST_HEAD(free_list); + struct list_head free_list; spin_lock_bh(&pernet->lock); - list_splice_init(&pernet->local_addr_list, &free_list); + free_list = pernet->local_addr_list; + INIT_LIST_HEAD_RCU(&pernet->local_addr_list); __reset_counters(pernet); pernet->next_id = 1; bitmap_zero(pernet->id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1); spin_unlock_bh(&pernet->lock); - mptcp_nl_remove_addrs_list(sock_net(skb->sk), &free_list); + + if (free_list.next == &pernet->local_addr_list) + return 0; + synchronize_rcu(); + + /* Adjust the pointers to free_list instead of pernet->local_addr_list */ + free_list.prev->next = &free_list; + free_list.next->prev = &free_list; + + mptcp_nl_remove_addrs_list(sock_net(skb->sk), &free_list); __flush_addrs(&free_list); return 0; } Patches currently in stable-queue which might be from matttbe@kernel.org are queue-6.1/selftests-mptcp-join-fix-local-endp-not-being-tracked.patch queue-6.1/mptcp-fix-race-in-mptcp_pm_nl_flush_addrs_doit.patch queue-6.1/mptcp-schedule-rtx-timer-only-after-pushing-data.patch queue-6.1/mptcp-ensure-context-reset-on-disconnect.patch queue-6.1/selftests-mptcp-pm-ensure-unknown-flags-are-ignored.patch queue-6.1/selftests-mptcp-check-no-dup-close-events-after-error.patch queue-6.1/selftests-mptcp-check-subflow-errors-in-close-events.patch