------------[ cut here ]------------
WARNING: CPU: 1 PID: 4055 at block/genhd.c:538 device_add_disk+0x60b/0xfc0 block/genhd.c:538
Modules linked in:
CPU: 1 PID: 4055 Comm: syz-executor.1 Not tainted 5.15.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:device_add_disk+0x60b/0xfc0 block/genhd.c:538
Code: 8e ec 07 00 00 8b 5d 00 bf 03 01 00 00 89 de e8 db 77 ac fd 81 fb 03 01 00 00 0f 85 69 fd ff ff e9 22 fd ff ff e8 15 6f ac fd <0f> 0b 41 bc 01 00 00 00 e9 6a fd ff ff e8 03 6f ac fd 0f 0b 41 bc
RSP: 0018:ffffc9000b87f458 EFLAGS: 00010246
RAX: 0000000000040000 RBX: 000000000000002b RCX: ffffc9000d171000
RDX: 0000000000040000 RSI: ffffffff83c9b48b RDI: 0000000000000003
RBP: ffff88807b59b000 R08: 0000000000000103 R09: ffff8880b9d32a8b
R10: ffffffff83c9b19c R11: 0000000000000000 R12: 00000000ffffffef
R13: ffff88807b59b080 R14: ffff88807b59b008 R15: ffff8880998d80c0
FS:  00007fabb7474700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff78ece4000 CR3: 000000002742c000 CR4: 00000000003506e0
Call Trace:
 add_disk include/linux/genhd.h:222 [inline]
 nbd_dev_add+0x83e/0xb90 drivers/block/nbd.c:1765
 nbd_genl_connect+0x11f3/0x1930 drivers/block/nbd.c:1889
 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:731
 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
 genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:792
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2510
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1935
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:724
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
 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: 0033:0x7fabb9efea39
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:00007fabb7474188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fabba011f60 RCX: 00007fabb9efea39
RDX: 0000000000000000 RSI: 00000000200002c0 RDI: 0000000000000005
RBP: 00007fabb9f58e8f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc757d9aef R14: 00007fabb7474300 R15: 0000000000022000