syzbot

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refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 35 at lib/refcount.c:25 refcount_warn_saturate+0x13a/0x1d0 lib/refcount.c:25
Modules linked in:
CPU: 1 UID: 0 PID: 35 Comm: kworker/u8:2 Not tainted 6.12.0-rc5-syzkaller-00194-g249cfa318fb1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: netns cleanup_net
RIP: 0010:refcount_warn_saturate+0x13a/0x1d0 lib/refcount.c:25
Code: c0 be 60 8c e8 37 9a 98 fc 90 0f 0b 90 90 eb b9 e8 8b a4 d7 fc c6 05 4d 95 49 0b 01 90 48 c7 c7 20 bf 60 8c e8 17 9a 98 fc 90 <0f> 0b 90 90 eb 99 e8 6b a4 d7 fc c6 05 2e 95 49 0b 01 90 48 c7 c7
RSP: 0018:ffffc90000ab73a0 EFLAGS: 00010246
RAX: c5b050024eecdc00 RBX: ffff8880247c7c3c RCX: ffff88801e6f1e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000002 R08: ffffffff8155d252 R09: 1ffffffff2859933
R10: dffffc0000000000 R11: fffffbfff2859934 R12: ffffffffffffffff
R13: ffff888067499000 R14: ffff8880247c7c3c R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2864a6 CR3: 0000000034cb4000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_inc include/linux/refcount.h:241 [inline]
 refcount_inc include/linux/refcount.h:258 [inline]
 fib_info_hold include/net/ip_fib.h:613 [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+0xee9/0x10b0 drivers/net/netdevsim/fib.c:1043
 call_fib_notifier+0x42/0x70 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:2203 [inline]
 fib_table_notify net/ipv4/fib_trie.c:2221 [inline]
 fib_notify+0x445/0x780 net/ipv4/fib_trie.c:2244
 fib_net_dump net/core/fib_notifier.c:71 [inline]
 register_fib_notifier+0x182/0x370 net/core/fib_notifier.c:109
 nsim_fib_create+0x902/0xa70 drivers/net/netdevsim/fib.c:1596
 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1483 [inline]
 nsim_dev_reload_up+0x3d1/0x8e0 drivers/net/netdevsim/dev.c:988
 devlink_reload+0x478/0x870 net/devlink/dev.c:474
 devlink_pernet_pre_exit+0x1f3/0x440 net/devlink/core.c:509
 ops_pre_exit_list net/core/net_namespace.c:163 [inline]
 cleanup_net+0x615/0xcc0 net/core/net_namespace.c:606
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>