------------[ cut here ]------------
WARNING: CPU: 1 PID: 23384 at block/genhd.c:523 __device_add_disk+0xb76/0xd10 block/genhd.c:523
Modules linked in:
CPU: 1 PID: 23384 Comm: syz-executor.3 Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__device_add_disk+0xb76/0xd10 block/genhd.c:523
Code: fb ff ff 4c 89 ef 89 44 24 28 e8 85 8a f6 fd 8b 44 24 28 e9 7a fb ff ff 4c 89 ef e8 04 8a f6 fd e9 e0 fb ff ff e8 1a 59 b0 fd <0f> 0b e9 97 fb ff ff 4c 89 ff e8 1b 8a f6 fd e9 b1 f6 ff ff 48 8b
RSP: 0018:ffffc900027bf3f0 EFLAGS: 00010246
RAX: 0000000000040000 RBX: ffff88807b74ac00 RCX: ffffc9000fe10000
RDX: 0000000000040000 RSI: ffffffff83c552b6 RDI: 0000000000000003
RBP: ffff88802f044400 R08: 0000000000000000 R09: ffffffff8bac2233
R10: ffffffff83c54e48 R11: 0000000000000000 R12: 0000000000000001
R13: ffff88807b74b09c R14: ffff88802f0444a0 R15: 0000000000000000
FS:  00007fa8053a6700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000306c6e7574 CR3: 0000000033fa3000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 add_disk include/linux/genhd.h:217 [inline]
 nbd_dev_add+0x73f/0x940 drivers/block/nbd.c:1733
 nbd_genl_connect+0x551/0x1820 drivers/block/nbd.c:1842
 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:739
 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
 genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:800
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:811
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:703 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:723
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2392
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2446
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2475
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa8053a6188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 0000000020000540 RDI: 0000000000000004
RBP: 00007fa8053a61d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007ffe2291868f R14: 00007fa8053a6300 R15: 0000000000022000