netlink: 'syz.1.984': attribute type 1 has an invalid length.
nbd: socks must be embedded in a SOCK_ITEM attr
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc5-syzkaller-00212-g9f735b6f8a77 #0 Not tainted
------------------------------------------------------
syz.1.984/9424 is trying to acquire lock:
ffff88812498f258 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: l2cap_sock_shutdown+0xd2/0x1130

but task is already holding lock:
ffff8881215c8670 (&nsock->tx_lock){+.+.}-{4:4}, at: sock_shutdown+0x14f/0x260

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (&nsock->tx_lock){+.+.}-{4:4}:
       lock_acquire+0x120/0x360
       __mutex_lock+0x182/0xe80
       nbd_queue_rq+0x257/0xf10
       blk_mq_dispatch_rq_list+0x4c0/0x1900
       __blk_mq_sched_dispatch_requests+0xda4/0x1570
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd0c/0xe00
       blk_mq_flush_plug_list+0x469/0x550
       __blk_flush_plug+0x3d3/0x4b0
       __submit_bio+0x2d3/0x5a0
       submit_bio_noacct_nocheck+0x4ab/0xb50
       block_read_full_folio+0x599/0x830
       filemap_read_folio+0x117/0x380
       do_read_cache_folio+0x350/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xa4/0xa50
       bdev_disk_changed+0x75f/0x14b0
       blkdev_get_whole+0x380/0x510
       bdev_open+0x31e/0xd30
       blkdev_open+0x3a8/0x510
       do_dentry_open+0xdf3/0x1970
       vfs_open+0x3b/0x340
       path_openat+0x2ee5/0x3830
       do_filp_open+0x1fa/0x410
       do_sys_openat2+0x121/0x1c0
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&cmd->lock){+.+.}-{4:4}:
       lock_acquire+0x120/0x360
       __mutex_lock+0x182/0xe80
       nbd_queue_rq+0xc8/0xf10
       blk_mq_dispatch_rq_list+0x4c0/0x1900
       __blk_mq_sched_dispatch_requests+0xda4/0x1570
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd0c/0xe00
       blk_mq_flush_plug_list+0x469/0x550
       __blk_flush_plug+0x3d3/0x4b0
       __submit_bio+0x2d3/0x5a0
       submit_bio_noacct_nocheck+0x4ab/0xb50
       block_read_full_folio+0x599/0x830
       filemap_read_folio+0x117/0x380
       do_read_cache_folio+0x350/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xa4/0xa50
       bdev_disk_changed+0x75f/0x14b0
       blkdev_get_whole+0x380/0x510
       bdev_open+0x31e/0xd30
       blkdev_open+0x3a8/0x510
       do_dentry_open+0xdf3/0x1970
       vfs_open+0x3b/0x340
       path_openat+0x2ee5/0x3830
       do_filp_open+0x1fa/0x410
       do_sys_openat2+0x121/0x1c0
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (set->srcu){.+.+}-{0:0}:
       lock_sync+0xba/0x160
       __synchronize_srcu+0x96/0x3a0
       elevator_switch+0x12b/0x5f0
       elevator_change+0x21b/0x320
       elevator_set_default+0x144/0x210
       blk_register_queue+0x35d/0x400
       __add_disk+0x677/0xd50
       add_disk_fwnode+0xfc/0x480
       nbd_dev_add+0x70e/0xb00
       nbd_init+0x21a/0x2d0
       do_one_initcall+0x236/0x820
       do_initcall_level+0x137/0x1f0
       do_initcalls+0x69/0xd0
       kernel_init_freeable+0x3d9/0x570
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x3fc/0x770
       ret_from_fork_asm+0x1a/0x30

-> #4 (&q->elevator_lock){+.+.}-{4:4}:
       lock_acquire+0x120/0x360
       __mutex_lock+0x182/0xe80
       elv_update_nr_hw_queues+0x87/0x2a0
       blk_mq_update_nr_hw_queues+0xd54/0x14c0
       nbd_start_device+0x16c/0xac0
       nbd_genl_connect+0x1250/0x1930
       genl_family_rcv_msg_doit+0x215/0x300
       genl_rcv_msg+0x60e/0x790
       netlink_rcv_skb+0x208/0x470
       genl_rcv+0x28/0x40
       netlink_unicast+0x75c/0x8e0
       netlink_sendmsg+0x805/0xb30
       __sock_sendmsg+0x21c/0x270
       ____sys_sendmsg+0x505/0x830
       ___sys_sendmsg+0x21f/0x2a0
       __x64_sys_sendmsg+0x19b/0x260
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&q->q_usage_counter(io)#49){++++}-{0:0}:
       lock_acquire+0x120/0x360
       blk_alloc_queue+0x538/0x620
       __blk_mq_alloc_disk+0x162/0x340
       nbd_dev_add+0x476/0xb00
       nbd_init+0x21a/0x2d0
       do_one_initcall+0x236/0x820
       do_initcall_level+0x137/0x1f0
       do_initcalls+0x69/0xd0
       kernel_init_freeable+0x3d9/0x570
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x3fc/0x770
       ret_from_fork_asm+0x1a/0x30

-> #2 (fs_reclaim){+.+.}-{0:0}:
       lock_acquire+0x120/0x360
       fs_reclaim_acquire+0x72/0x100
       kmem_cache_alloc_noprof+0x44/0x3c0
       mas_alloc_nodes+0x2e9/0x8e0
       mas_preallocate+0x3ad/0x6f0
       vma_link+0x102/0x450
       insert_vm_struct+0x199/0x260
       create_init_stack_vma+0x2de/0x680
       alloc_bprm+0x476/0x5b0
       kernel_execve+0x9b/0x9f0
       try_to_run_init_process+0x13/0x60
       kernel_init+0xad/0x1d0
       ret_from_fork+0x3fc/0x770
       ret_from_fork_asm+0x1a/0x30

-> #1 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x120/0x360
       __might_fault+0xcc/0x130
       _copy_from_user+0x28/0xb0
       l2cap_sock_setsockopt+0x6ed/0x1d20
       do_sock_setsockopt+0x17c/0x1b0
       __x64_sys_setsockopt+0x13f/0x1b0
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       lock_acquire+0x120/0x360
       lock_sock_nested+0x48/0x100
       l2cap_sock_shutdown+0xd2/0x1130
       nbd_mark_nsock_dead+0x2e9/0x560
       sock_shutdown+0x15e/0x260
       nbd_config_put+0x342/0x790
       nbd_genl_connect+0x1282/0x1930
       genl_family_rcv_msg_doit+0x215/0x300
       genl_rcv_msg+0x60e/0x790
       netlink_rcv_skb+0x208/0x470
       genl_rcv+0x28/0x40
       netlink_unicast+0x75c/0x8e0
       netlink_sendmsg+0x805/0xb30
       __sock_sendmsg+0x21c/0x270
       ____sys_sendmsg+0x505/0x830
       ___sys_sendmsg+0x21f/0x2a0
       __x64_sys_sendmsg+0x19b/0x260
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP --> &cmd->lock --> &nsock->tx_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&nsock->tx_lock);
                               lock(&cmd->lock);
                               lock(&nsock->tx_lock);
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP);

 *** DEADLOCK ***

4 locks held by syz.1.984/9424:
 #0: ffffffff8f581e30 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f581c48 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
 #2: ffff888020b5da30 (&nbd->config_lock){+.+.}-{4:4}, at: refcount_dec_and_mutex_lock+0x30/0xa0
 #3: ffff8881215c8670 (&nsock->tx_lock){+.+.}-{4:4}, at: sock_shutdown+0x14f/0x260

stack backtrace:
CPU: 1 UID: 0 PID: 9424 Comm: syz.1.984 Not tainted 6.16.0-rc5-syzkaller-00212-g9f735b6f8a77 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_circular_bug+0x2ee/0x310
 check_noncircular+0x134/0x160
 validate_chain+0xb9b/0x2140
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 lock_sock_nested+0x48/0x100
 l2cap_sock_shutdown+0xd2/0x1130
 nbd_mark_nsock_dead+0x2e9/0x560
 sock_shutdown+0x15e/0x260
 nbd_config_put+0x342/0x790
 nbd_genl_connect+0x1282/0x1930
 genl_family_rcv_msg_doit+0x215/0x300
 genl_rcv_msg+0x60e/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x75c/0x8e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7cd438e9a9
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:00007f7cd21f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7cd45b5fa0 RCX: 00007f7cd438e9a9
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000000000000013
RBP: 00007f7cd4410d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7cd45b5fa0 R15: 00007ffd998fd558
 </TASK>
block nbd1: shutting down sockets
