syzbot

netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 14859 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Modules linked in:
CPU: 1 UID: 0 PID: 14859 Comm: kworker/u8:22 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: netns cleanup_net
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Code: 00 00 e8 f9 f0 3d fd 5b 41 5e e9 d1 a2 4a 06 cc e8 eb f0 3d fd c6 05 58 8c 60 0a 01 90 48 c7 c7 a0 9a 3e 8b e8 87 38 02 fd 90 <0f> 0b 90 90 eb d7 e8 cb f0 3d fd c6 05 39 8c 60 0a 01 90 48 c7 c7
RSP: 0000:ffffc9000cd2f228 EFLAGS: 00010246
RAX: a4ec5d55d57a3e00 RBX: 0000000000000002 RCX: ffff88803bf50000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed101712487b R12: dffffc0000000000
R13: ffff88806ab9c020 R14: ffff88802f9fd63c R15: ffff88806ab9c000
FS:  0000000000000000(0000) GS:ffff888126cc2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2d8cc5 CR3: 00000000320b4000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:-1 [inline]
 __refcount_inc include/linux/refcount.h:366 [inline]
 refcount_inc include/linux/refcount.h:383 [inline]
 fib_info_hold include/net/ip_fib.h:629 [inline]
 nsim_fib4_prepare_event drivers/net/netdevsim/fib.c:930 [inline]
 nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1000 [inline]
 nsim_fib_event_nb+0xec6/0x10b0 drivers/net/netdevsim/fib.c:1043
 call_fib_notifier+0x45/0x80 net/core/fib_notifier.c:24
 call_fib_entry_notifier net/ipv4/fib_trie.c:90 [inline]
 fib_leaf_notify net/ipv4/fib_trie.c:2175 [inline]
 fib_table_notify net/ipv4/fib_trie.c:2193 [inline]
 fib_notify+0x359/0x5d0 net/ipv4/fib_trie.c:2216
 fib_net_dump net/core/fib_notifier.c:69 [inline]
 register_fib_notifier+0x184/0x360 net/core/fib_notifier.c:107
 nsim_fib_create+0x843/0x9d0 drivers/net/netdevsim/fib.c:1596
 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1528 [inline]
 nsim_dev_reload_up+0x36b/0x780 drivers/net/netdevsim/dev.c:1003
 devlink_reload+0x4f8/0x8d0 net/devlink/dev.c:474
 devlink_pernet_pre_exit+0x1d9/0x3d0 net/devlink/core.c:509
 ops_pre_exit_list net/core/net_namespace.c:161 [inline]
 ops_undo_list+0x187/0x990 net/core/net_namespace.c:234
 cleanup_net+0x4de/0x820 net/core/net_namespace.c:695
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>