======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.1005/8860 is trying to acquire lock:
ffff8880241e99a0 (msk_lock-AF_INET6){+.+.}-{0:0}, at: inet_sk_diag_fill+0xe40/0x19d0 net/ipv4/inet_diag.c:342

but task is already holding lock:
ffffc900018a2aa0 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffffc900018a2aa0 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:95 [inline]
ffffc900018a2aa0 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump+0x8f4/0x12a0 net/mptcp/mptcp_diag.c:194

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&h->lhash2[i].lock){+.+.}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
       _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
       spin_lock include/linux/spinlock.h:364 [inline]
       inet_unhash+0xd0/0x540 net/ipv4/inet_hashtables.c:662
       tcp_set_state+0x35d/0x520 net/ipv4/tcp.c:2635
       __tcp_close+0x91/0xf10 net/ipv4/tcp.c:2760
       __mptcp_close_ssk+0x1ea/0x460 net/mptcp/protocol.c:2393
       __mptcp_destroy_sock+0x39e/0x6e0 net/mptcp/protocol.c:2831
       mptcp_close+0x5a6/0x9f0 net/mptcp/protocol.c:2888
       inet_release+0x139/0x180 net/ipv4/af_inet.c:432
       __sock_release net/socket.c:651 [inline]
       sock_close+0xbf/0x210 net/socket.c:1346
       __fput+0x212/0x8c0 fs/file_table.c:311
       task_work_run+0x125/0x1a0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
       __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (k-sk_lock-AF_INET6/1){+.+.}-{0:0}:
       lock_sock_fast_nested include/net/sock.h:1784 [inline]
       mptcp_close+0x296/0x9f0 net/mptcp/protocol.c:2870
       inet_release+0x139/0x180 net/ipv4/af_inet.c:432
       __sock_release net/socket.c:651 [inline]
       sock_release+0x7b/0x140 net/socket.c:679
       mptcp_pm_nl_create_listen_socket net/mptcp/pm_netlink.c:1125 [inline]
       mptcp_nl_cmd_add_addr+0x9e1/0xc50 net/mptcp/pm_netlink.c:1416
       genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
       genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
       genl_rcv_msg+0xd0b/0xfa0 net/netlink/genetlink.c:792
       netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2519
       genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
       netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
       netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1340
       netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1919
       sock_sendmsg_nosec net/socket.c:706 [inline]
       __sock_sendmsg net/socket.c:718 [inline]
       ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2446
       ___sys_sendmsg+0x236/0x2e0 net/socket.c:2500
       __sys_sendmsg net/socket.c:2529 [inline]
       __do_sys_sendmsg net/socket.c:2538 [inline]
       __se_sys_sendmsg+0x1b7/0x2a0 net/socket.c:2536
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (msk_lock-AF_INET6){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       lock_sock_fast include/net/sock.h:1776 [inline]
       mptcp_diag_get_info+0x1f2/0x9e0 net/mptcp/mptcp_diag.c:224
       inet_sk_diag_fill+0xe40/0x19d0 net/ipv4/inet_diag.c:342
       sk_diag_dump net/mptcp/mptcp_diag.c:24 [inline]
       mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:122 [inline]
       mptcp_diag_dump+0xcc2/0x12a0 net/mptcp/mptcp_diag.c:194
       __inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
       netlink_dump+0x6d2/0xdd0 net/netlink/af_netlink.c:2291
       __netlink_dump_start+0x4e4/0x720 net/netlink/af_netlink.c:2398
       netlink_dump_start include/linux/netlink.h:260 [inline]
       inet_diag_handler_cmd+0x1d2/0x2b0 net/ipv4/inet_diag.c:1344
       sock_diag_rcv_msg+0x15c/0x3e0 net/core/sock_diag.c:-1
       netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2519
       sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276
       netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
       netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1340
       netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1919
       sock_sendmsg_nosec net/socket.c:706 [inline]
       __sock_sendmsg net/socket.c:718 [inline]
       sock_write_iter+0x2a6/0x3a0 net/socket.c:1090
       do_iter_readv_writev+0x47d/0x5f0 fs/read_write.c:-1
       do_iter_write+0x1f8/0x7a0 fs/read_write.c:855
       vfs_writev fs/read_write.c:928 [inline]
       do_writev+0x281/0x480 fs/read_write.c:971
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  msk_lock-AF_INET6 --> k-sk_lock-AF_INET6/1 --> &h->lhash2[i].lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&h->lhash2[i].lock);
                               lock(k-sk_lock-AF_INET6/1);
                               lock(&h->lhash2[i].lock);
  lock(msk_lock-AF_INET6);

 *** DEADLOCK ***

6 locks held by syz.6.1005/8860:
 #0: ffffffff8d456fe8 (sock_diag_mutex){+.+.}-{3:3}, at: sock_diag_rcv+0x17/0x40 net/core/sock_diag.c:275
 #1: ffffffff8d456ea8 (sock_diag_table_mutex){+.+.}-{3:3}, at: __sock_diag_cmd net/core/sock_diag.c:229 [inline]
 #1: ffffffff8d456ea8 (sock_diag_table_mutex){+.+.}-{3:3}, at: sock_diag_rcv_msg+0x20e/0x3e0 net/core/sock_diag.c:265
 #2: ffff888017bd7690 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{3:3}, at: __netlink_dump_start+0xf5/0x720 net/netlink/af_netlink.c:2363
 #3: ffffffff8d530968 (inet_diag_table_mutex){+.+.}-{3:3}, at: inet_diag_lock_handler net/ipv4/inet_diag.c:63 [inline]
 #3: ffffffff8d530968 (inet_diag_table_mutex){+.+.}-{3:3}, at: __inet_diag_dump+0x181/0x380 net/ipv4/inet_diag.c:1177
 #4: ffffffff8c31ef60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #5: ffffc900018a2aa0 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
 #5: ffffc900018a2aa0 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:95 [inline]
 #5: ffffc900018a2aa0 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump+0x8f4/0x12a0 net/mptcp/mptcp_diag.c:194

stack backtrace:
CPU: 1 PID: 8860 Comm: syz.6.1005 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 lock_sock_fast include/net/sock.h:1776 [inline]
 mptcp_diag_get_info+0x1f2/0x9e0 net/mptcp/mptcp_diag.c:224
 inet_sk_diag_fill+0xe40/0x19d0 net/ipv4/inet_diag.c:342
 sk_diag_dump net/mptcp/mptcp_diag.c:24 [inline]
 mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:122 [inline]
 mptcp_diag_dump+0xcc2/0x12a0 net/mptcp/mptcp_diag.c:194
 __inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
 netlink_dump+0x6d2/0xdd0 net/netlink/af_netlink.c:2291
 __netlink_dump_start+0x4e4/0x720 net/netlink/af_netlink.c:2398
 netlink_dump_start include/linux/netlink.h:260 [inline]
 inet_diag_handler_cmd+0x1d2/0x2b0 net/ipv4/inet_diag.c:1344
 sock_diag_rcv_msg+0x15c/0x3e0 net/core/sock_diag.c:-1
 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2519
 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 sock_write_iter+0x2a6/0x3a0 net/socket.c:1090
 do_iter_readv_writev+0x47d/0x5f0 fs/read_write.c:-1
 do_iter_write+0x1f8/0x7a0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_writev+0x281/0x480 fs/read_write.c:971
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fa3a351c019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa3a1732028 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fa3a37a4180 RCX: 00007fa3a351c019
RDX: 0000000000000001 RSI: 0000200000000280 RDI: 0000000000000005
RBP: 00007fa3a35b300c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3a37a4218 R14: 00007fa3a37a4180 R15: 00007ffd09414408
 </TASK>
BUG: sleeping function called from invalid context at net/core/sock.c:3291
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 8860, name: syz.6.1005
INFO: lockdep is turned off.
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 PID: 8860 Comm: syz.6.1005 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 ___might_sleep+0x493/0x610 kernel/sched/core.c:9658
 __lock_sock_fast+0x2f/0xe0 net/core/sock.c:3291
 lock_sock_fast include/net/sock.h:1778 [inline]
 mptcp_diag_get_info+0x1fe/0x9e0 net/mptcp/mptcp_diag.c:224
 inet_sk_diag_fill+0xe40/0x19d0 net/ipv4/inet_diag.c:342
 sk_diag_dump net/mptcp/mptcp_diag.c:24 [inline]
 mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:122 [inline]
 mptcp_diag_dump+0xcc2/0x12a0 net/mptcp/mptcp_diag.c:194
 __inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
 netlink_dump+0x6d2/0xdd0 net/netlink/af_netlink.c:2291
 __netlink_dump_start+0x4e4/0x720 net/netlink/af_netlink.c:2398
 netlink_dump_start include/linux/netlink.h:260 [inline]
 inet_diag_handler_cmd+0x1d2/0x2b0 net/ipv4/inet_diag.c:1344
 sock_diag_rcv_msg+0x15c/0x3e0 net/core/sock_diag.c:-1
 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2519
 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 sock_write_iter+0x2a6/0x3a0 net/socket.c:1090
 do_iter_readv_writev+0x47d/0x5f0 fs/read_write.c:-1
 do_iter_write+0x1f8/0x7a0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_writev+0x281/0x480 fs/read_write.c:971
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fa3a351c019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa3a1732028 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fa3a37a4180 RCX: 00007fa3a351c019
RDX: 0000000000000001 RSI: 0000200000000280 RDI: 0000000000000005
RBP: 00007fa3a35b300c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3a37a4218 R14: 00007fa3a37a4180 R15: 00007ffd09414408
 </TASK>