------------[ cut here ]------------
WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib6_event_init drivers/net/netdevsim/fib.c:831 [inline], CPU#3: syz.2.1237/9937
WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib6_prepare_event drivers/net/netdevsim/fib.c:947 [inline], CPU#3: syz.2.1237/9937
WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1003 [inline], CPU#3: syz.2.1237/9937
WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib_event_nb+0xb73/0xec0 drivers/net/netdevsim/fib.c:1043, CPU#3: syz.2.1237/9937
Modules linked in:
CPU: 3 UID: 0 PID: 9937 Comm: syz.2.1237 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:nsim_fib6_event_init drivers/net/netdevsim/fib.c:831 [inline]
RIP: 0010:nsim_fib6_prepare_event drivers/net/netdevsim/fib.c:947 [inline]
RIP: 0010:nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1003 [inline]
RIP: 0010:nsim_fib_event_nb+0xb73/0xec0 drivers/net/netdevsim/fib.c:1043
Code: 20 48 8b 5c 24 28 e8 ac 00 be fa e8 a7 00 be fa 44 89 ee 44 89 ff e8 7c fa bd fa 45 39 ef 0f 84 dd fd ff ff e8 8e 00 be fa 90 <0f> 0b 90 e9 cf fd ff ff e8 80 00 be fa 49 8d 7c 24 38 be 01 00 00
RSP: 0018:ffffc9000d447130 EFLAGS: 00010287
RAX: 0000000000000b63 RBX: 0000000000000001 RCX: ffffc90007ac2000
RDX: 0000000000080000 RSI: ffffffff8700ff02 RDI: ffff8880221afc18
RBP: ffffc9000d447280 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88802c3ad4b0 R12: ffff88802d05b000
R13: 0000000000000001 R14: ffff888036455300 R15: ffff8880221afc00
FS:  00007fa47d3d06c0(0000) GS:ffff8880d6bf1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa47d3cff98 CR3: 0000000034947000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 notifier_call_chain+0xbc/0x3e0 kernel/notifier.c:85
 atomic_notifier_call_chain+0x71/0x1c0 kernel/notifier.c:223
 call_fib_notifiers+0x33/0x70 net/core/fib_notifier.c:35
 call_fib6_multipath_entry_notifiers+0x112/0x170 net/ipv6/ip6_fib.c:425
 ip6_route_multipath_add+0xb4f/0x1c30 net/ipv6/route.c:5536
 inet6_rtm_newroute+0xe4/0x1a0 net/ipv6/route.c:5658
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646
 __sys_sendmsg+0x16d/0x220 net/socket.c:2678
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa47c58f7c9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa47d3d0038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fa47c7e5fa0 RCX: 00007fa47c58f7c9
RDX: 0000000000040000 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007fa47c613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa47c7e6038 R14: 00007fa47c7e5fa0 R15: 00007ffd0d494d68
 </TASK>