------------[ cut here ]------------
WARNING: net/mptcp/subflow.c:1527 at subflow_data_ready+0x40b/0x790 net/mptcp/subflow.c:1527, CPU#0: syz.4.761/8671
Modules linked in:
CPU: 0 UID: 0 PID: 8671 Comm: syz.4.761 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:subflow_data_ready+0x40b/0x790 net/mptcp/subflow.c:1527
Code: 89 ee e8 e8 32 5b f6 40 84 ed 75 21 e8 9e 38 5b f6 44 89 fe bf 07 00 00 00 e8 31 33 5b f6 41 83 ff 07 74 09 e8 86 38 5b f6 90 <0f> 0b 90 e8 7d 38 5b f6 48 89 df e8 f5 ac ff ff 31 ff 89 c5 89 c6
RSP: 0018:ffffc900043e7778 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888039164240 RCX: ffffffff8b63ae2f
RDX: ffff8880332424c0 RSI: ffffffff8b63ae3a RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000007
R10: 000000000000000b R11: ffff888033242ff0 R12: ffff8880258f9900
R13: 1ffff9200087ceef R14: ffff88805e62cc00 R15: 000000000000000b
FS:  00007f66a7a926c0(0000) GS:ffff8880d68f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f66a7a50d58 CR3: 000000006196a000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 tcp_data_ready+0x114/0x5a0 net/ipv4/tcp_input.c:5371
 tcp_data_queue+0x1ac2/0x4ff0 net/ipv4/tcp_input.c:5461
 tcp_rcv_state_process+0xfb6/0x6540 net/ipv4/tcp_input.c:7185
 tcp_v6_do_rcv+0x7b8/0x1dc0 net/ipv6/tcp_ipv6.c:1630
 sk_backlog_rcv include/net/sock.h:1177 [inline]
 __release_sock+0x158/0x450 net/core/sock.c:3213
 release_sock+0x5a/0x220 net/core/sock.c:3795
 mptcp_connect+0x914/0xae0 net/mptcp/protocol.c:3991
 __inet_stream_connect+0x915/0xf50 net/ipv4/af_inet.c:679
 inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:750
 __sys_connect_file+0x141/0x1a0 net/socket.c:2089
 __sys_connect+0x13b/0x160 net/socket.c:2108
 __do_sys_connect net/socket.c:2114 [inline]
 __se_sys_connect net/socket.c:2111 [inline]
 __x64_sys_connect+0x72/0xb0 net/socket.c:2111
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f66a6b8f7c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f66a7a92038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f66a6de5fa0 RCX: 00007f66a6b8f7c9
RDX: 000000000000001c RSI: 0000200000000040 RDI: 0000000000000003
RBP: 00007f66a6c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f66a6de6038 R14: 00007f66a6de5fa0 R15: 00007ffc8a13d3e8
 </TASK>