syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/4325 is trying to acquire lock:
ffff88807f048120 (sk_lock-AF_INET){+.+.}-{0:0}, at: inet_sk_diag_fill+0xef6/0x1b50 net/ipv4/inet_diag.c:342

but task is already holding lock:
ffffc900018c5c20 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffffc900018c5c20 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:95 [inline]
ffffc900018c5c20 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump+0x911/0x1290 net/mptcp/mptcp_diag.c:194

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&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_hash+0xe3/0x960 net/ipv4/inet_hashtables.c:613
       inet_csk_listen_start+0x22f/0x320 net/ipv4/inet_connection_sock.c:1115
       inet_listen+0x2e1/0x590 net/ipv4/af_inet.c:231
       __sys_listen+0x19d/0x220 net/socket.c:1764
       __do_sys_listen net/socket.c:1773 [inline]
       __se_sys_listen net/socket.c:1771 [inline]
       __x64_sys_listen+0x56/0x60 net/socket.c:1771
       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 (sk_lock-AF_INET){+.+.}-{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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       lock_sock_fast include/net/sock.h:1763 [inline]
       mptcp_diag_get_info+0x1db/0x990 net/mptcp/mptcp_diag.c:224
       inet_sk_diag_fill+0xef6/0x1b50 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+0xcca/0x1290 net/mptcp/mptcp_diag.c:194
       __inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
       inet_diag_dump_compat+0x161/0x200 net/ipv4/inet_diag.c:1288
       netlink_dump+0x676/0xcd0 net/netlink/af_netlink.c:2283
       __netlink_dump_start+0x523/0x700 net/netlink/af_netlink.c:2386
       netlink_dump_start include/linux/netlink.h:258 [inline]
       inet_diag_rcv_msg_compat+0x1e9/0x3c0 net/ipv4/inet_diag.c:1323
       sock_diag_rcv_msg+0x164/0x3e0 net/core/sock_diag.c:-1
       netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2507
       sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x8ab/0xbc0 net/netlink/af_netlink.c:1918
       sock_sendmsg_nosec net/socket.c:706 [inline]
       __sock_sendmsg net/socket.c:718 [inline]
       ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2446
       ___sys_sendmsg+0x1f0/0x260 net/socket.c:2500
       __sys_sendmsg net/socket.c:2529 [inline]
       __do_sys_sendmsg net/socket.c:2538 [inline]
       __se_sys_sendmsg+0x190/0x250 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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&h->lhash2[i].lock);
                               lock(sk_lock-AF_INET);
                               lock(&h->lhash2[i].lock);
  lock(sk_lock-AF_INET);

 *** DEADLOCK ***

6 locks held by syz.0.17/4325:
 #0: ffffffff8d242568 (sock_diag_mutex){+.+.}-{3:3}, at: sock_diag_rcv+0x17/0x40 net/core/sock_diag.c:275
 #1: ffffffff8d242428 (sock_diag_table_mutex){+.+.}-{3:3}, at: sock_diag_rcv_msg+0x14a/0x3e0 net/core/sock_diag.c:255
 #2: ffff888074b05698 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{3:3}, at: __netlink_dump_start+0x11f/0x700 net/netlink/af_netlink.c:2352
 #3: ffffffff8d31c948 (inet_diag_table_mutex){+.+.}-{3:3}, at: inet_diag_lock_handler net/ipv4/inet_diag.c:63 [inline]
 #3: ffffffff8d31c948 (inet_diag_table_mutex){+.+.}-{3:3}, at: __inet_diag_dump+0x181/0x380 net/ipv4/inet_diag.c:1177
 #4: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #5: ffffc900018c5c20 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
 #5: ffffc900018c5c20 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:95 [inline]
 #5: ffffc900018c5c20 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump+0x911/0x1290 net/mptcp/mptcp_diag.c:194

stack backtrace:
CPU: 0 PID: 4325 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 lock_sock_fast include/net/sock.h:1763 [inline]
 mptcp_diag_get_info+0x1db/0x990 net/mptcp/mptcp_diag.c:224
 inet_sk_diag_fill+0xef6/0x1b50 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+0xcca/0x1290 net/mptcp/mptcp_diag.c:194
 __inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
 inet_diag_dump_compat+0x161/0x200 net/ipv4/inet_diag.c:1288
 netlink_dump+0x676/0xcd0 net/netlink/af_netlink.c:2283
 __netlink_dump_start+0x523/0x700 net/netlink/af_netlink.c:2386
 netlink_dump_start include/linux/netlink.h:258 [inline]
 inet_diag_rcv_msg_compat+0x1e9/0x3c0 net/ipv4/inet_diag.c:1323
 sock_diag_rcv_msg+0x164/0x3e0 net/core/sock_diag.c:-1
 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2507
 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ab/0xbc0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2446
 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2500
 __sys_sendmsg net/socket.c:2529 [inline]
 __do_sys_sendmsg net/socket.c:2538 [inline]
 __se_sys_sendmsg+0x190/0x250 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
RIP: 0033:0x7f1abe634749
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:00007ffc8472a5a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1abe88afa0 RCX: 00007f1abe634749
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007f1abe6b8f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1abe88afa0 R14: 00007f1abe88afa0 R15: 0000000000000003
 </TASK>
BUG: sleeping function called from invalid context at net/core/sock.c:3288
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4325, name: syz.0.17
INFO: lockdep is turned off.
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 0 PID: 4325 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 ___might_sleep+0x47c/0x600 kernel/sched/core.c:9658
 __lock_sock_fast+0x2f/0xe0 net/core/sock.c:3288
 lock_sock_fast include/net/sock.h:1765 [inline]
 mptcp_diag_get_info+0x1e7/0x990 net/mptcp/mptcp_diag.c:224
 inet_sk_diag_fill+0xef6/0x1b50 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+0xcca/0x1290 net/mptcp/mptcp_diag.c:194
 __inet_diag_dump+0x1f6/0x380 net/ipv4/inet_diag.c:1179
 inet_diag_dump_compat+0x161/0x200 net/ipv4/inet_diag.c:1288
 netlink_dump+0x676/0xcd0 net/netlink/af_netlink.c:2283
 __netlink_dump_start+0x523/0x700 net/netlink/af_netlink.c:2386
 netlink_dump_start include/linux/netlink.h:258 [inline]
 inet_diag_rcv_msg_compat+0x1e9/0x3c0 net/ipv4/inet_diag.c:1323
 sock_diag_rcv_msg+0x164/0x3e0 net/core/sock_diag.c:-1
 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2507
 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ab/0xbc0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2446
 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2500
 __sys_sendmsg net/socket.c:2529 [inline]
 __do_sys_sendmsg net/socket.c:2538 [inline]
 __se_sys_sendmsg+0x190/0x250 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
RIP: 0033:0x7f1abe634749
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:00007ffc8472a5a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1abe88afa0 RCX: 00007f1abe634749
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007f1abe6b8f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1abe88afa0 R14: 00007f1abe88afa0 R15: 0000000000000003
 </TASK>