FAILED: patch "[PATCH] mptcp: prevent MPC handshake on port-based signal endpoints" failed to apply to 6.1-stable tree
Subsystems (3)
[email protected]
maintainerThe patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 3d041393ea8c815f773020fb4a995331a69c0139
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024101814-postal-swarm-0080@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 3d041393ea8c815f773020fb4a995331a69c0139 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <[email protected]>
Date: Mon, 14 Oct 2024 16:06:00 +0200
Subject: [PATCH] mptcp: prevent MPC handshake on port-based signal endpoints
Syzkaller reported a lockdep splat:
============================================
WARNING: possible recursive locking detected 6.11.0-rc6-syzkaller-00019-g67784a74e258 #0 Not tainted
--------------------------------------------
syz-executor364/5113 is trying to acquire lock:
ffff8880449f1958 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880449f1958 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328
but task is already holding lock:
ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(k-slock-AF_INET);
lock(k-slock-AF_INET);*** DEADLOCK ***
May be due to missing lock nesting notation
7 locks held by syz-executor364/5113:
#0: ffff8880449f0e18 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline] #0: ffff8880449f0e18 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg+0x153/0x1b10 net/mptcp/protocol.c:1806 #1: ffff88803fe39ad8 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline] #1: ffff88803fe39ad8 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg_fastopen+0x11f/0x530 net/mptcp/protocol.c:1727 #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: __ip_queue_xmit+0x5f/0x1b80 net/ipv4/ip_output.c:470 #3: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #3: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #3: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x45f/0x1390 net/ipv4/ip_output.c:228 #4: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: local_lock_acquire include/linux/local_lock_internal.h:29 [inline] #4: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: process_backlog+0x33b/0x15b0 net/core/dev.c:6104 #5: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #5: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #5: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish+0x230/0x5f0 net/ipv4/ip_input.c:232 #6: ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #6: ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328
stack backtrace: CPU: 0 UID: 0 PID: 5113 Comm: syz-executor364 Not tainted 6.11.0-rc6-syzkaller-00019-g67784a74e258 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119 check_deadlock kernel/locking/lockdep.c:3061 [inline] validate_chain+0x15d3/0x5900 kernel/locking/lockdep.c:3855 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759 __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] sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328 mptcp_sk_clone_init+0x32/0x13c0 net/mptcp/protocol.c:3279 subflow_syn_recv_sock+0x931/0x1920 net/mptcp/subflow.c:874 tcp_check_req+0xfe4/0x1a20 net/ipv4/tcp_minisocks.c:853 tcp_v4_rcv+0x1c3e/0x37f0 net/ipv4/tcp_ipv4.c:2267 ip_protocol_deliver_rcu+0x22e/0x440 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x341/0x5f0 net/ipv4/ip_input.c:233 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 __netif_receive_skb_one_core net/core/dev.c:5661 [inline] __netif_receive_skb+0x2bf/0x650 net/core/dev.c:5775 process_backlog+0x662/0x15b0 net/core/dev.c:6108 __napi_poll+0xcb/0x490 net/core/dev.c:6772 napi_poll net/core/dev.c:6841 [inline] net_rx_action+0x89b/0x1240 net/core/dev.c:6963 handle_softirqs+0x2c4/0x970 kernel/softirq.c:554 do_softirq+0x11b/0x1e0 kernel/softirq.c:455 </IRQ> <TASK> __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:908 [inline] __dev_queue_xmit+0x1763/0x3e90 net/core/dev.c:4450 dev_queue_xmit include/linux/netdevice.h:3105 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0xd41/0x1390 net/ipv4/ip_output.c:235 ip_local_out net/ipv4/ip_output.c:129 [inline] __ip_queue_xmit+0x118c/0x1b80 net/ipv4/ip_output.c:535 __tcp_transmit_skb+0x2544/0x3b30 net/ipv4/tcp_output.c:1466 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6542 [inline] tcp_rcv_state_process+0x2c32/0x4570 net/ipv4/tcp_input.c:6729 tcp_v4_do_rcv+0x77d/0xc70 net/ipv4/tcp_ipv4.c:1934 sk_backlog_rcv include/net/sock.h:1111 [inline] __release_sock+0x214/0x350 net/core/sock.c:3004 release_sock+0x61/0x1f0 net/core/sock.c:3558 mptcp_sendmsg_fastopen+0x1ad/0x530 net/mptcp/protocol.c:1733 mptcp_sendmsg+0x1884/0x1b10 net/mptcp/protocol.c:1812 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x1a6/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597 ___sys_sendmsg net/socket.c:2651 [inline] __sys_sendmmsg+0x3b2/0x740 net/socket.c:2737 __do_sys_sendmmsg net/socket.c:2766 [inline] __se_sys_sendmmsg net/socket.c:2763 [inline] __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2763 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f04fb13a6b9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 01 1a 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd651f42d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f04fb13a6b9 RDX: 0000000000000001 RSI: 0000000020000d00 RDI: 0000000000000004 RBP: 00007ffd651f4310 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000020000080 R11: 0000000000000246 R12: 00000000000f4240 R13: 00007f04fb187449 R14: 00007ffd651f42f4 R15: 00007ffd651f4300 </TASK>
As noted by Cong Wang, the splat is false positive, but the code path leading to the report is an unexpected one: a client is attempting an MPC handshake towards the in-kernel listener created by the in-kernel PM for a port based signal endpoint.
Such connection will be never accepted; many of them can make the listener queue full and preventing the creation of MPJ subflow via such listener - its intended role.
Explicitly detect this scenario at initial-syn time and drop the incoming MPC request.
net/mptcp/mib.c +1 -0
@@ -17,6 +17,7 @@ static const struct snmp_mib mptcp_snmp_list[] = {SNMP_MIB_ITEM ("MPCapableFallbackSYNACK" ,MPTCP_MIB_MPCAPABLEACTIVEFALLBACK ),SNMP_MIB_ITEM ("MPCapableSYNTXDrop" ,MPTCP_MIB_MPCAPABLEACTIVEDROP ),SNMP_MIB_ITEM ("MPCapableSYNTXDisabled" ,MPTCP_MIB_MPCAPABLEACTIVEDISABLED ), +SNMP_MIB_ITEM ("MPCapableEndpAttempt" ,MPTCP_MIB_MPCAPABLEENDPATTEMPT ),SNMP_MIB_ITEM ("MPFallbackTokenInit" ,MPTCP_MIB_TOKENFALLBACKINIT ),SNMP_MIB_ITEM ("MPTCPRetrans" ,MPTCP_MIB_RETRANSSEGS ), SNMP_MIB_ITEM("MPJoinNoTokenFound", MPTCP_MIB_JOINNOTOKEN),
net/mptcp/mib.h +1 -0
@@ -12,6 +12,7 @@ enum linux_mptcp_mib_field {MPTCP_MIB_MPCAPABLEACTIVEFALLBACK ,/* Client-side fallback during 3-way handshake */ MPTCP_MIB_MPCAPABLEACTIVEDROP ,/* Client-side fallback due to a MPC drop */ MPTCP_MIB_MPCAPABLEACTIVEDISABLED ,/* Client-side disabled due to past issues */ +MPTCP_MIB_MPCAPABLEENDPATTEMPT ,/* Prohibited MPC to port-based endp */ MPTCP_MIB_TOKENFALLBACKINIT ,/* Could not init/allocate token */ MPTCP_MIB_RETRANSSEGS ,/* Segments retransmitted at the MPTCP-level */ MPTCP_MIB_JOINNOTOKEN, /* Received MP_JOIN but the token was not found */
net/mptcp/pm_netlink.c +1 -0
@@ -1121,6 +1121,7 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,*/ inet_sk_state_store (newsk,TCP_LISTEN );lock_sock (ssk); +WRITE_ONCE (mptcp_subflow_ctx (ssk)->pm_listener, true); err =__inet_listen_sk (ssk, backlog);if (!err)mptcp_event_pm_listener (ssk,MPTCP_EVENT_LISTENER_CREATED );
net/mptcp/protocol.h +1 -0
@@ -535,6 +535,7 @@ struct mptcp_subflow_context { __unused :8 ;bool data_avail;bool scheduled; +bool pm_listener;/* a listener managed by the kernel PM? */ u32 remote_nonce;u64 thmac;u32 local_nonce;
net/mptcp/subflow.c +11 -0
@@ -132,6 +132,13 @@ static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason) } } +static int subflow_reset_req_endp (struct request_sock *req,struct sk_buff *skb) +{ +SUBFLOW_REQ_INC_STATS (req,MPTCP_MIB_MPCAPABLEENDPATTEMPT ); +subflow_add_reset_reason (skb,MPTCP_RST_EPROHIBIT ); +return -EPERM ; +} +/* Init mptcp request socket. * * Returns an error code if a JOIN has failed and a TCP reset
@@ -165,6 +172,8 @@ static int subflow_check_req(struct request_sock *req,if (opt_mp_capable) {SUBFLOW_REQ_INC_STATS (req,MPTCP_MIB_MPCAPABLEPASSIVE ); +if (unlikely (listener->pm_listener)) +return subflow_reset_req_endp (req, skb);if (opt_mp_join)return 0 ; }else if (opt_mp_join) {
@@ -172,6 +181,8 @@ static int subflow_check_req(struct request_sock *req,if (mp_opt.backup)SUBFLOW_REQ_INC_STATS (req,MPTCP_MIB_JOINSYNBACKUPRX ); + }else if (unlikely (listener->pm_listener)) { +return subflow_reset_req_endp (req, skb); }if (opt_mp_capable && listener->request_mptcp) {