netdevsim netdevsim6 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#1: kworker/u8:5/71 Modules linked in: CPU: 1 UID: 0 PID: 71 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: netns cleanup_net RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25 Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 6b a0 13 fd 48 8d 3d 84 78 89 0b 67 48 0f b9 3a eb 4a e8 58 a0 13 fd 48 8d 3d 81 78 89 0b <67> 48 0f b9 3a eb 37 e8 45 a0 13 fd 48 8d 3d 7e 78 89 0b 67 48 0f RSP: 0018:ffffc900015e7270 EFLAGS: 00010293 RAX: ffffffff84b22178 RBX: 0000000000000002 RCX: ffff88801d71bd80 RDX: 0000000000000000 RSI: ffffffff8f10faa0 RDI: ffffffff903b9a00 RBP: 0000000000000000 R08: ffff88801d71bd80 R09: 0000000000000005 R10: 0000000000000004 R11: 0000000000000000 R12: ffff888056319000 R13: ffff888056319000 R14: ffff888069c0e43c R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff88812538c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000556c5a593360 CR3: 0000000077dc6000 CR4: 00000000003526f0 DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: __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+0x101e/0x1210 drivers/net/netdevsim/fib.c:1043 call_fib_notifier+0x45/0x80 net/core/fib_notifier.c:25 call_fib_entry_notifier net/ipv4/fib_trie.c:90 [inline] fib_leaf_notify net/ipv4/fib_trie.c:2176 [inline] fib_table_notify net/ipv4/fib_trie.c:2194 [inline] fib_notify+0x36b/0x5e0 net/ipv4/fib_trie.c:2217 fib_net_dump net/core/fib_notifier.c:70 [inline] register_fib_notifier+0x184/0x360 net/core/fib_notifier.c:108 nsim_fib_create+0x877/0xa10 drivers/net/netdevsim/fib.c:1596 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1604 [inline] nsim_dev_reload_up+0x374/0x7c0 drivers/net/netdevsim/dev.c:1058 devlink_reload+0x4f8/0x8c0 net/devlink/dev.c:475 devlink_pernet_pre_exit+0x1ff/0x420 net/devlink/core.c:558 ops_pre_exit_list net/core/net_namespace.c:161 [inline] ops_undo_list+0x187/0x940 net/core/net_namespace.c:234 cleanup_net+0x56b/0x800 net/core/net_namespace.c:702 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 ---------------- Code disassembly (best guess): 0: eb 66 jmp 0x68 2: 85 db test %ebx,%ebx 4: 74 3e je 0x44 6: 83 fb 01 cmp $0x1,%ebx 9: 75 4c jne 0x57 b: e8 6b a0 13 fd call 0xfd13a07b 10: 48 8d 3d 84 78 89 0b lea 0xb897884(%rip),%rdi # 0xb89789b 17: 67 48 0f b9 3a ud1 (%edx),%rdi 1c: eb 4a jmp 0x68 1e: e8 58 a0 13 fd call 0xfd13a07b 23: 48 8d 3d 81 78 89 0b lea 0xb897881(%rip),%rdi # 0xb8978ab * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb 37 jmp 0x68 31: e8 45 a0 13 fd call 0xfd13a07b 36: 48 8d 3d 7e 78 89 0b lea 0xb89787e(%rip),%rdi # 0xb8978bb 3d: 67 addr32 3e: 48 rex.W 3f: 0f .byte 0xf