======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/6003 is trying to acquire lock:
ffff888079800b18 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1693 [inline]
ffff888079800b18 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: vsock_linger+0x2e9/0x4f0 net/vmw_vsock/af_vsock.c:1066

but task is already holding lock:
ffffffff8f81d228 (vsock_register_mutex){+.+.}-{4:4}, at: vsock_assign_transport+0xfa/0x770 net/vmw_vsock/af_vsock.c:469

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (vsock_register_mutex){+.+.}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
       vsock_registered_transport_cid net/vmw_vsock/af_vsock.c:560 [inline]
       vsock_find_cid net/vmw_vsock/af_vsock.c:570 [inline]
       __vsock_bind+0xdb/0xc20 net/vmw_vsock/af_vsock.c:752
       vsock_bind+0xdc/0x130 net/vmw_vsock/af_vsock.c:1002
       __sys_bind_socket net/socket.c:1874 [inline]
       __sys_bind+0x2c6/0x3e0 net/socket.c:1905
       __do_sys_bind net/socket.c:1910 [inline]
       __se_sys_bind net/socket.c:1908 [inline]
       __x64_sys_bind+0x7a/0x90 net/socket.c:1908
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sk_lock-AF_VSOCK){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       lock_sock_nested+0x48/0x100 net/core/sock.c:3752
       lock_sock include/net/sock.h:1693 [inline]
       vsock_linger+0x2e9/0x4f0 net/vmw_vsock/af_vsock.c:1066
       virtio_transport_close net/vmw_vsock/virtio_transport_common.c:1271 [inline]
       virtio_transport_release+0x2da/0x7e0 net/vmw_vsock/virtio_transport_common.c:1291
       vsock_assign_transport+0x385/0x770 net/vmw_vsock/af_vsock.c:502
       vsock_connect+0x5a6/0xe20 net/vmw_vsock/af_vsock.c:1578
       __sys_connect_file net/socket.c:2102 [inline]
       __sys_connect+0x316/0x440 net/socket.c:2121
       __do_sys_connect net/socket.c:2127 [inline]
       __se_sys_connect net/socket.c:2124 [inline]
       __x64_sys_connect+0x7a/0x90 net/socket.c:2124
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(vsock_register_mutex);
                               lock(sk_lock-AF_VSOCK);
                               lock(vsock_register_mutex);
  lock(sk_lock-AF_VSOCK);

 *** DEADLOCK ***

1 lock held by syz.0.17/6003:
 #0: ffffffff8f81d228 (vsock_register_mutex){+.+.}-{4:4}, at: vsock_assign_transport+0xfa/0x770 net/vmw_vsock/af_vsock.c:469

stack backtrace:
CPU: 1 UID: 0 PID: 6003 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 lock_sock_nested+0x48/0x100 net/core/sock.c:3752
 lock_sock include/net/sock.h:1693 [inline]
 vsock_linger+0x2e9/0x4f0 net/vmw_vsock/af_vsock.c:1066
 virtio_transport_close net/vmw_vsock/virtio_transport_common.c:1271 [inline]
 virtio_transport_release+0x2da/0x7e0 net/vmw_vsock/virtio_transport_common.c:1291
 vsock_assign_transport+0x385/0x770 net/vmw_vsock/af_vsock.c:502
 vsock_connect+0x5a6/0xe20 net/vmw_vsock/af_vsock.c:1578
 __sys_connect_file net/socket.c:2102 [inline]
 __sys_connect+0x316/0x440 net/socket.c:2121
 __do_sys_connect net/socket.c:2127 [inline]
 __se_sys_connect net/socket.c:2124 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2124
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f888978efc9
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:00007fff13bc0bf8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f88899e5fa0 RCX: 00007f888978efc9
RDX: 0000000000000010 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007f8889811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f88899e5fa0 R14: 00007f88899e5fa0 R15: 0000000000000003
 </TASK>