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 7659423EAB7; Wed, 28 Jan 2026 15:33:37 +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=1769614417; cv=none; b=bu6uLJlaB6DXJ6KjlWWwWZ6JxhqOzsEPdBySPvlccOzmhvJ93vlcJHAN6YBl53/i5+jP7lgttE8XObroP7RGSylAs0XGRGGQiYapCX47c1EPZxKtdQDA9snO8eiPccnAy7djCdxlAK4arwBWUTUfyklZmb6Cvye+83ZoVZ6svoI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769614417; c=relaxed/simple; bh=8OuJuf8xaSDWrIHUGGbxxi0+Q22oTz0+GoPs2jZigfI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lAazhSNwBYkn7KTDfYxn3ryDPSNMb74ZQhulj/06iEsM+A9ya7b3VhOigyt3z4/Yv3BB8Z0w3oN7cDAyqqj1lJYjuwSV7OQdg6JSIlyxlJIJXfCiYwky2FfeWiP5U0kYM4hT8d5K0MiiVBlwBDx5KUT1o5lDyyNtOGkE/dFPy4U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kyz6En61; 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="kyz6En61" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3CB0C4CEF1; Wed, 28 Jan 2026 15:33:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1769614417; bh=8OuJuf8xaSDWrIHUGGbxxi0+Q22oTz0+GoPs2jZigfI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kyz6En61iDQyq8BiqRARx/5sdQp/LDhUjkBAN8vRNp/fl1pSUe61lppoj1KUQWox1 6My2RJBEzralyC4a58rOX6zA7eGQ8KGmwdF0mAhsdqj5c3lB6qKFTjRUddpO6f6UML 8xnbvnC2RfCrRTISieolZxVyJ6mpKXdTlCjMWxF0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+7312e82745f7fa2526db@syzkaller.appspotmail.com, Eric Dumazet , James Chapman , Guillaume Nault , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 129/254] l2tp: avoid one data-race in l2tp_tunnel_del_work() Date: Wed, 28 Jan 2026 16:21:45 +0100 Message-ID: <20260128145349.461647186@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260128145344.698118637@linuxfoundation.org> References: <20260128145344.698118637@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 7a29f6bf60f2590fe5e9c4decb451e19afad2bcf ] We should read sk->sk_socket only when dealing with kernel sockets. syzbot reported the following data-race: BUG: KCSAN: data-race in l2tp_tunnel_del_work / sk_common_release write to 0xffff88811c182b20 of 8 bytes by task 5365 on cpu 0: sk_set_socket include/net/sock.h:2092 [inline] sock_orphan include/net/sock.h:2118 [inline] sk_common_release+0xae/0x230 net/core/sock.c:4003 udp_lib_close+0x15/0x20 include/net/udp.h:325 inet_release+0xce/0xf0 net/ipv4/af_inet.c:437 __sock_release net/socket.c:662 [inline] sock_close+0x6b/0x150 net/socket.c:1455 __fput+0x29b/0x650 fs/file_table.c:468 ____fput+0x1c/0x30 fs/file_table.c:496 task_work_run+0x131/0x1a0 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:44 [inline] exit_to_user_mode_loop+0x1fe/0x740 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x1e1/0x2b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff88811c182b20 of 8 bytes by task 827 on cpu 1: l2tp_tunnel_del_work+0x2f/0x1a0 net/l2tp/l2tp_core.c:1418 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340 worker_thread+0x582/0x770 kernel/workqueue.c:3421 kthread+0x489/0x510 kernel/kthread.c:463 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 value changed: 0xffff88811b818000 -> 0x0000000000000000 Fixes: d00fa9adc528 ("l2tp: fix races with tunnel socket close") Reported-by: syzbot+7312e82745f7fa2526db@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6968b029.050a0220.58bed.0016.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: James Chapman Reviewed-by: Guillaume Nault Link: https://patch.msgid.link/20260115092139.3066180-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/l2tp/l2tp_core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 70da78ab95202..e0ca08ebd16a9 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1250,8 +1250,6 @@ static void l2tp_tunnel_del_work(struct work_struct *work) { struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, del_work); - struct sock *sk = tunnel->sock; - struct socket *sock = sk->sk_socket; l2tp_tunnel_closeall(tunnel); @@ -1259,6 +1257,8 @@ static void l2tp_tunnel_del_work(struct work_struct *work) * the sk API to release it here. */ if (tunnel->fd < 0) { + struct socket *sock = tunnel->sock->sk_socket; + if (sock) { kernel_sock_shutdown(sock, SHUT_RDWR); sock_release(sock); -- 2.51.0