WARNING: CPU: 1 PID: 18585 at kernel/fork.c:408 free_task+0xf8/0x120 kernel/fork.c:408 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 18585 Comm: syz-executor.3 Not tainted 4.19.75 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 panic+0x263/0x507 kernel/panic.c:185 kobject: 'loop4' (00000000913b741e): kobject_uevent_env kobject: 'loop4' (00000000913b741e): fill_kobj_path: path = '/devices/virtual/block/loop4' __warn.cold+0x20/0x4a kernel/panic.c:540 report_bug+0x263/0x2b0 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] fixup_bug arch/x86/kernel/traps.c:173 [inline] do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1037 RIP: 0010:free_task+0xf8/0x120 kernel/fork.c:408 Code: 48 8b 3d fb 36 3c 08 4c 89 e6 e8 d3 8c 63 00 5b 41 5c 41 5d 5d c3 e8 c7 32 2d 00 4c 89 e7 e8 2f 6f 09 00 eb d6 e8 b8 32 2d 00 <0f> 0b e9 6a ff ff ff e8 0c c6 63 00 eb ab 4c 89 ef e8 02 c6 63 00 RSP: 0018:ffff8880ae907db0 EFLAGS: 00010206 RAX: ffff88809b4aa100 RBX: 0000000000000001 RCX: ffffffff813e2f31 RDX: 0000000000000100 RSI: ffffffff813e2fc8 RDI: 0000000000000005 kobject: 'loop4' (00000000913b741e): kobject_uevent_env RBP: ffff8880ae907dc8 R08: ffff88809b4aa100 R09: ffffed100946e338 R10: ffffed100946e337 R11: ffff88804a3719bb R12: ffff88804a370680 R13: ffff88804a3719b8 R14: ffff888094f5eac8 R15: ffffffff813fa710 kobject: 'loop4' (00000000913b741e): fill_kobj_path: path = '/devices/virtual/block/loop4' __put_task_struct+0x20f/0x4c0 kernel/fork.c:689 put_task_struct include/linux/sched/task.h:96 [inline] delayed_put_task_struct+0x1fb/0x350 kernel/exit.c:181 __rcu_reclaim kernel/rcu/rcu.h:236 [inline] rcu_do_batch kernel/rcu/tree.c:2584 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2864 [inline] rcu_process_callbacks+0xba0/0x1a30 kernel/rcu/tree.c:2881 __do_softirq+0x25c/0x921 kernel/softirq.c:292 kobject: 'loop4' (00000000913b741e): kobject_uevent_env do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1091 do_softirq.part.0+0x11a/0x170 kernel/softirq.c:336 do_softirq kernel/softirq.c:328 [inline] __local_bh_enable_ip+0x211/0x270 kernel/softirq.c:189 kobject: 'loop4' (00000000913b741e): fill_kobj_path: path = '/devices/virtual/block/loop4' local_bh_enable include/linux/bottom_half.h:32 [inline] get_next_corpse net/netfilter/nf_conntrack_core.c:1928 [inline] nf_ct_iterate_cleanup+0x217/0x4e0 net/netfilter/nf_conntrack_core.c:1951 caif:caif_disconnect_client(): nothing to disconnect nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2036 [inline] nf_ct_iterate_cleanup_net+0x133/0x190 net/netfilter/nf_conntrack_core.c:2021 masq_device_event+0xe2/0x120 net/ipv4/netfilter/nf_nat_masquerade_ipv4.c:100 notifier_call_chain+0xc2/0x230 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1747 call_netdevice_notifiers net/core/dev.c:1765 [inline] dev_close_many+0x33f/0x6f0 net/core/dev.c:1517 rollback_registered_many+0x33f/0xda0 net/core/dev.c:7982 kobject: 'loop4' (00000000913b741e): kobject_uevent_env kobject: 'loop4' (00000000913b741e): fill_kobj_path: path = '/devices/virtual/block/loop4' rollback_registered+0x109/0x1d0 net/core/dev.c:8047 unregister_netdevice_queue net/core/dev.c:9096 [inline] unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9089 unregister_netdevice include/linux/netdevice.h:2605 [inline] __tun_detach+0xd8a/0x1040 drivers/net/tun.c:737 tun_detach drivers/net/tun.c:754 [inline] tun_chr_close+0xe0/0x180 drivers/net/tun.c:3257 __fput+0x2dd/0x8b0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4136f1 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffcab058f70 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004136f1 RDX: 0000001b30d20000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000001 R08: 00000000dec7843d R09: 00000000dec78441 R10: 00007ffcab059050 R11: 0000000000000293 R12: 000000000075bfc8 R13: 00000000001dfbbd R14: 00000000007605d8 R15: 000000000075bfd4 Kernel Offset: disabled Rebooting in 86400 seconds..