BUG: unable to handle kernel NULL pointer dereference at 0000000000000578
IP: read_pnet include/net/net_namespace.h:270 [inline]
IP: dev_net include/linux/netdevice.h:2041 [inline]
IP: snmp6_unregister_dev+0x12/0x70 net/ipv6/proc.c:308
PGD 20b7ac067 P4D 20b7ac067 PUD 20ab2d067 PMD 0 
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 19054 Comm: syz-executor6 Not tainted 4.15.0-rc3-next-20171214+ #67
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:read_pnet include/net/net_namespace.h:270 [inline]
RIP: 0010:dev_net include/linux/netdevice.h:2041 [inline]
RIP: 0010:snmp6_unregister_dev+0x12/0x70 net/ipv6/proc.c:308
RSP: 0018:ffffc90000ef7b08 EFLAGS: 00010216
RAX: 0000000000000000 RBX: ffff8801fb53c400 RCX: ffffffff822a18ef
RDX: 00000000000024fa RSI: ffffc900033d5000 RDI: ffff8801fb53c400
RBP: ffffc90000ef7b18 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8801fb53c400
R13: ffff8801fb53c400 R14: ffffc90000ef7cd0 R15: ffff8801fa4ae000
FS:  00007f7925989700(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000578 CR3: 000000020aaaa004 CR4: 00000000001606e0
DR0: fffffffffffffffe DR1: 2000000000000879 DR2: 0000000000000001
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 addrconf_ifdown+0x70e/0x780 net/ipv6/addrconf.c:3607
 addrconf_notify+0x86/0xd50 net/ipv6/addrconf.c:3514
 notifier_call_chain+0x41/0xc0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x32/0x60 net/core/dev.c:1679
 call_netdevice_notifiers net/core/dev.c:1697 [inline]
 rollback_registered_many+0x330/0x490 net/core/dev.c:7288
 rollback_registered+0x59/0x90 net/core/dev.c:7330
 unregister_netdevice_queue+0xa5/0xf0 net/core/dev.c:8311
 br_dev_delete+0xa9/0xc0 net/bridge/br_if.c:320
 br_del_bridge+0x57/0x80 net/bridge/br_if.c:421
 br_ioctl_deviceless_stub+0x13f/0x400 net/bridge/br_ioctl.c:380
 sock_ioctl+0x2af/0x320 net/socket.c:1028
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xaf/0x840 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a09
RSP: 002b:00007f7925988c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452a09
RDX: 00000000207fb000 RSI: 00000000000089a1 RDI: 0000000000000013
RBP: 000000000000055d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f5158
R13: 00000000ffffffff R14: 00007f79259896d4 R15: 0000000000000000
Code: fe ff ff ff eb e4 bb f4 ff ff ff eb dd 66 90 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 54 53 48 89 fb e8 51 8a 01 ff 48 8b 03 <48> 8b 80 78 05 00 00 48 83 b8 18 02 00 00 00 74 3e e8 38 8a 01 
RIP: read_pnet include/net/net_namespace.h:270 [inline] RSP: ffffc90000ef7b08
RIP: dev_net include/linux/netdevice.h:2041 [inline] RSP: ffffc90000ef7b08
RIP: snmp6_unregister_dev+0x12/0x70 net/ipv6/proc.c:308 RSP: ffffc90000ef7b08
CR2: 0000000000000578
---[ end trace 80414a7c559fb9b5 ]---