------------[ cut here ]------------ refcount_t: increment on 0; use-after-free. WARNING: CPU: 0 PID: 8321 at lib/refcount.c:156 refcount_inc_checked lib/refcount.c:156 [inline] WARNING: CPU: 0 PID: 8321 at lib/refcount.c:156 refcount_inc_checked+0x61/0x70 lib/refcount.c:154 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 8321 Comm: syz-executor.0 Not tainted 5.3.0-rc1+ #86 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+0x2dc/0x755 kernel/panic.c:219 __warn.cold+0x20/0x4c kernel/panic.c:576 report_bug+0x263/0x2b0 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:179 [inline] fixup_bug arch/x86/kernel/traps.c:174 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1026 RIP: 0010:refcount_inc_checked lib/refcount.c:156 [inline] RIP: 0010:refcount_inc_checked+0x61/0x70 lib/refcount.c:154 Code: 1d 48 87 64 06 31 ff 89 de e8 cb a3 35 fe 84 db 75 dd e8 82 a2 35 fe 48 c7 c7 c0 02 c6 87 c6 05 28 87 64 06 01 e8 67 05 07 fe <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 RSP: 0018:ffff8880ae809bf0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000100 RSI: ffffffff815c5bd6 RDI: ffffed1015d01370 RBP: ffff8880ae809c00 R08: ffff88809c488700 R09: fffffbfff11b4285 R10: fffffbfff11b4284 R11: ffffffff88da1423 R12: ffff888093fed4c0 R13: ffff888093fed4a8 R14: ffff88809393a608 R15: ffff88809393a5e0 sock_hold include/net/sock.h:649 [inline] sk_add_node include/net/sock.h:701 [inline] nr_insert_socket+0x2d/0xe0 net/netrom/af_netrom.c:137 nr_rx_frame+0x1605/0x1e73 net/netrom/af_netrom.c:1023 nr_loopback_timer+0x7b/0x170 net/netrom/nr_loopback.c:59 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1322 expire_timers kernel/time/timer.c:1366 [inline] __run_timers kernel/time/timer.c:1685 [inline] __run_timers kernel/time/timer.c:1653 [inline] run_timer_softirq+0x697/0x17a0 kernel/time/timer.c:1698 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:537 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1095 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:828 RIP: 0010:__local_bh_disable_ip+0x0/0x1b0 kernel/softirq.c:111 Code: ff ff ff 48 c7 c7 90 f1 d2 88 e8 0b 1a 67 00 e9 5d ff ff ff 48 c7 c7 90 f1 d2 88 e8 fa 19 67 00 eb 81 0f 1f 84 00 00 00 00 00 <55> 48 89 e5 41 55 41 54 49 89 fc 53 89 f3 65 8b 05 43 57 bc 7e a9 RSP: 0018:ffff88807b547700 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: ffff88809c488700 RBX: 0000000000003261 RCX: ffffffff85d1f1cb RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffffffff85d1f12f RBP: ffff88807b547768 R08: ffff88809c488700 R09: fffffbfff118c5f9 R10: fffffbfff118c5f8 R11: ffffffff88c62fc3 R12: 0000000000010000 R13: 0000000000000261 R14: 0000000000000001 R15: dffffc0000000000 nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2122 [inline] nf_ct_iterate_cleanup_net+0x133/0x190 net/netfilter/nf_conntrack_core.c:2107 masq_device_event+0xb5/0xe0 net/netfilter/nf_nat_masquerade.c:88 notifier_call_chain+0xc2/0x230 kernel/notifier.c:95 __raw_notifier_call_chain kernel/notifier.c:396 [inline] raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749 call_netdevice_notifiers_extack net/core/dev.c:1761 [inline] call_netdevice_notifiers net/core/dev.c:1775 [inline] dev_close_many+0x33f/0x6f0 net/core/dev.c:1518 rollback_registered_many+0x35a/0xdf0 net/core/dev.c:8173 rollback_registered+0x109/0x1d0 net/core/dev.c:8238 unregister_netdevice_queue net/core/dev.c:9285 [inline] unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9278 unregister_netdevice include/linux/netdevice.h:2631 [inline] __tun_detach+0xd8a/0x1040 drivers/net/tun.c:723 tun_detach drivers/net/tun.c:740 [inline] tun_chr_close+0xe0/0x180 drivers/net/tun.c:3439 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x92f/0x2eb0 kernel/exit.c:878 do_group_exit+0x135/0x360 kernel/exit.c:982 __do_sys_exit_group kernel/exit.c:993 [inline] __se_sys_exit_group kernel/exit.c:991 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:991 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459829 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffd8d4ab9a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000016 RCX: 0000000000459829 RDX: 0000000000413430 RSI: 0000000000a74ef0 RDI: 0000000000000000 RBP: 00000000004be569 R08: 000000000000000c R09: 0000000000000000 R10: 00005555564bb940 R11: 0000000000000246 R12: 00007ffd8d4acc50 R13: 00005555564c4980 R14: 0000000000000000 R15: 00007ffd8d4adce0 Kernel Offset: disabled Rebooting in 86400 seconds..