------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 0 PID: 30400 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31
Modules linked in:
CPU: 0 PID: 30400 Comm: syz-executor.2 Not tainted 5.12.0-rc4-next-20210326-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31
Code: 1d 5b 7f e6 09 31 ff 89 de e8 7d b6 a7 fd 84 db 75 e0 e8 c4 af a7 fd 48 c7 c7 60 3e c2 89 c6 05 3b 7f e6 09 01 e8 04 00 fe 04 <0f> 0b eb c4 e8 a8 af a7 fd 0f b6 1d 2a 7f e6 09 31 ff 89 de e8 48
RSP: 0018:ffffc900190676a0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815c3fd5 RDI: fffff5200320cec6
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815bd77e R11: 0000000000000000 R12: dffffc0000000000
R13: ffffc900190677e8 R14: ffff88801d340568 R15: ffff888012fc9880
FS:  00007f1a4510c700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000970004 CR3: 000000008744e000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_dec include/linux/refcount.h:344 [inline]
 refcount_dec include/linux/refcount.h:359 [inline]
 dev_put include/linux/netdevice.h:4135 [inline]
 unregister_netdevice_many+0x1225/0x1790 net/core/dev.c:11037
 unregister_netdevice_queue+0x2dd/0x3c0 net/core/dev.c:10934
 register_netdevice+0x10d6/0x1500 net/core/dev.c:10292
 register_netdev+0x2d/0x50 net/core/dev.c:10380
 sit_init_net+0x3a4/0xb20 net/ipv6/sit.c:1917
 ops_init+0xaf/0x470 net/core/net_namespace.c:140
 setup_net+0x40f/0xa30 net/core/net_namespace.c:333
 copy_net_ns+0x31e/0x760 net/core/net_namespace.c:474
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 copy_namespaces+0x385/0x440 kernel/nsproxy.c:178
 copy_process+0x2bfe/0x71b0 kernel/fork.c:2111
 kernel_clone+0xe7/0xab0 kernel/fork.c:2501
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2618
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
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:00007f1a4510c188 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000380
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffd197b255f R14: 00007f1a4510c300 R15: 0000000000022000