------------[ cut here ]------------ refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 0 PID: 11688 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31 Modules linked in: CPU: 0 PID: 11688 Comm: syz-executor.4 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:ffffc90002a47990 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000040000 RSI: ffffffff815c3fd5 RDI: fffff52000548f24 RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815bd77e R11: 0000000000000000 R12: dffffc0000000000 R13: ffffc90002a47ad8 R14: ffff888014f28568 R15: ffff8880266f6880 FS: 00007f3be0a94700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32624000 CR3: 000000001ce72000 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 unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:226 ksys_unshare+0x445/0x8e0 kernel/fork.c:2994 __do_sys_unshare kernel/fork.c:3062 [inline] __se_sys_unshare kernel/fork.c:3060 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3060 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:00007f3be0a94188 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000060000000 RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffd886229bf R14: 00007f3be0a94300 R15: 0000000000022000