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Wed, 21 Feb 2024 10:32:23 -0500 X-MC-Unique: NveUzipxMcSZB-3g6RRbfQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F119B3816443 for ; Wed, 21 Feb 2024 15:32:22 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.45.224.94]) by smtp.corp.redhat.com (Postfix) with ESMTP id 803FE492BE7 for ; Wed, 21 Feb 2024 15:32:22 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH v2 mptcp-net 1/2] mptcp: fix possible deadlock in subflow diag Date: Wed, 21 Feb 2024 16:32:16 +0100 Message-ID: In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" Syzbot and Eric reported a lockdep splat in the subflow diag: WARNING: possible circular locking dependency detected 6.8.0-rc4-syzkaller-00212-g40b9385dd8e6 #0 Not tainted syz-executor.2/24141 is trying to acquire lock: ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline] ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137 but task is already holding lock: ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: inet_diag_dump_icsk+0x39f/0x1f80 net/ipv4/inet_diag.c:1038 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&h->lhash2[i].lock){+.+.}-{2:2}: lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __inet_hash+0x335/0xbe0 net/ipv4/inet_hashtables.c:743 inet_csk_listen_start+0x23a/0x320 net/ipv4/inet_connection_sock.c:1261 __inet_listen_sk+0x2a2/0x770 net/ipv4/af_inet.c:217 inet_listen+0xa3/0x110 net/ipv4/af_inet.c:239 rds_tcp_listen_init+0x3fd/0x5a0 net/rds/tcp_listen.c:316 rds_tcp_init_net+0x141/0x320 net/rds/tcp.c:577 ops_init+0x352/0x610 net/core/net_namespace.c:136 __register_pernet_operations net/core/net_namespace.c:1214 [inline] register_pernet_operations+0x2cb/0x660 net/core/net_namespace.c:1283 register_pernet_device+0x33/0x80 net/core/net_namespace.c:1370 rds_tcp_init+0x62/0xd0 net/rds/tcp.c:735 do_one_initcall+0x238/0x830 init/main.c:1236 do_initcall_level+0x157/0x210 init/main.c:1298 do_initcalls+0x3f/0x80 init/main.c:1314 kernel_init_freeable+0x42f/0x5d0 init/main.c:1551 kernel_init+0x1d/0x2a0 init/main.c:1441 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242 -> #0 (k-sk_lock-AF_INET6){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 lock_sock_fast include/net/sock.h:1723 [inline] subflow_get_info+0x166/0xd20 net/mptcp/diag.c:28 tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline] tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137 inet_sk_diag_fill+0x10ed/0x1e00 net/ipv4/inet_diag.c:345 inet_diag_dump_icsk+0x55b/0x1f80 net/ipv4/inet_diag.c:1061 __inet_diag_dump+0x211/0x3a0 net/ipv4/inet_diag.c:1263 inet_diag_dump_compat+0x1c1/0x2d0 net/ipv4/inet_diag.c:1371 netlink_dump+0x59b/0xc80 net/netlink/af_netlink.c:2264 __netlink_dump_start+0x5df/0x790 net/netlink/af_netlink.c:2370 netlink_dump_start include/linux/netlink.h:338 [inline] inet_diag_rcv_msg_compat+0x209/0x4c0 net/ipv4/inet_diag.c:1405 sock_diag_rcv_msg+0xe7/0x410 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:280 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367 netlink_sendmsg+0xa3b/0xd70 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 As noted by Eric we can break the lock dependency chain avoid dumping any extended info for the mptcp subflow listener: nothing actually useful is presented there. Fixes: b8adb69a7d29 ("mptcp: fix lockless access in subflow ULP diag") Reported-by: Eric Dumazet Suggested-by: Eric Dumazet Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) --- net/mptcp/diag.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c index 6ff6f14674aa..7017dd60659d 100644 --- a/net/mptcp/diag.c +++ b/net/mptcp/diag.c @@ -21,6 +21,9 @@ static int subflow_get_info(struct sock *sk, struct sk_bu= ff *skb) bool slow; int err; =20 + if (inet_sk_state_load(sk) =3D=3D TCP_LISTEN) + return 0; + start =3D nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP); if (!start) return -EMSGSIZE; --=20 2.43.0 From nobody Wed May 15 12:58:28 2024 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 CB28E7F7FD for ; Wed, 21 Feb 2024 15:32:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708529548; cv=none; b=EJvDT8Dr/h4JXMzYifZ93BZEEFooOJ6qi+aWyrYcJRhhsdXQ5lZqQ/cqQxYj8qolO89GWjR+XVJptx1ibvZiB4tqYkxW3iuI0d1iCODhSAasdML0A6otIMyTrlDd1MCjmabaKaSHNRPKtNtGLt6SMI/KZLCDSo/iZz4KY902UVw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708529548; c=relaxed/simple; bh=0QRvSeroLkeJAwlqqkMvCIRyJS6sqRirMjYrqgXIr5U=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lx1I5SZuEmleafO/MGtHS13FcB4V9jKg37Q9MRGweOxGcDlHix3gHRbJ4g707oOs5J6B2KgOsMRp5xxzuO3YHwOvVUE33W1qW3OON9JyX7fu8gcYaSBj7TQrW9mt8TlglyDWYp99ASJjE7Nh751y0XaXcFa0kCBxHiQlC6hsHzI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Y7Xaglv8; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Y7Xaglv8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1708529545; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vcLaHCG6y05YdNmGoIJp4DQJyz6FcavN8ax3H019LeU=; b=Y7Xaglv8t1h+7OrEwYJiUkQQLq5yAKjMSPsEOl8oZom3+UF6zlVQrskpsUT5u6DLbhtFUB y46zlBA2MY93vR961x8Z67UTdE4U3hejC2px+re78W8Li72l6E9msN8YDH2prm7vrgqWx1 wj8LEpUUrJuLfqhScxpsemWzKMv4jjk= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-2-4FRDA7UHOJ6oYafCvjLo0A-1; Wed, 21 Feb 2024 10:32:23 -0500 X-MC-Unique: 4FRDA7UHOJ6oYafCvjLo0A-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B276A282D3C4 for ; Wed, 21 Feb 2024 15:32:23 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.45.224.94]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4166A492BE7 for ; Wed, 21 Feb 2024 15:32:23 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH v2 mptcp-net 2/2] selftests: mptcp: explicitly trigger the listener diag code-path Date: Wed, 21 Feb 2024 16:32:17 +0100 Message-ID: <6bf1e9da6cb4ec0c6de1acd37995137b74dcc8bf.1708529444.git.pabeni@redhat.com> In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" The mptcp diag interface already experienced a few locking bugs that lockdep and appropriate coverage have detected in advance. Let's add a test-case triggering the relevant code path, to prevent similar issues in the future. Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) --- tools/testing/selftests/net/mptcp/diag.sh | 24 +++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/self= tests/net/mptcp/diag.sh index 60a7009ce1b5..e3c28479b5a4 100755 --- a/tools/testing/selftests/net/mptcp/diag.sh +++ b/tools/testing/selftests/net/mptcp/diag.sh @@ -81,6 +81,15 @@ chk_msk_nr() __chk_msk_nr "grep -c token:" "$@" } =20 +chk_listener_nr() +{ + local expected=3D$1 + local msg=3D"$2" + + __chk_nr "ss -inmlHMON $ns | wc -l" "$expected" "$msg - mptcp" 0 + __chk_nr "ss -inmlHtON $ns | wc -l" "$expected" "$msg - subflows" +} + wait_msk_nr() { local condition=3D"grep -c token:" @@ -279,5 +288,20 @@ flush_pids chk_msk_inuse 0 "many->0" chk_msk_cestab 0 "many->0" =20 +chk_listener_nr 0 "no listener sockets" +NR_SERVERS=3D100 +for I in $(seq 1 $NR_SERVERS); do + ip netns exec $ns ./mptcp_connect -p $((I + 20001)) -l 0.0.0.0 2>&1 >/dev= /null & + mptcp_lib_wait_local_port_listen $ns $((I + 20001)) +done + +chk_listener_nr $NR_SERVERS "many listener sockets" + +# gracefull termination +for I in $(seq 1 $NR_SERVERS); do + echo a | ip netns exec $ns ./mptcp_connect -p $((I + 20001)) 127.0.0.1 2>= &1 >/dev/null +done +flush_pids + mptcp_lib_result_print_all_tap exit $ret --=20 2.43.0