[ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.22' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 36.862582] ------------[ cut here ]------------ [ 36.867715] refcount_t: underflow; use-after-free. [ 36.873474] WARNING: CPU: 0 PID: 8288 at lib/refcount.c:280 refcount_dec_not_one+0x1bc/0x1d0 [ 36.882073] Kernel panic - not syncing: panic_on_warn set ... [ 36.882073] [ 36.889429] CPU: 0 PID: 8288 Comm: systemd-udevd Not tainted 4.19.211-syzkaller #0 [ 36.897127] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023 [ 36.906472] Call Trace: [ 36.909054] dump_stack+0x1fc/0x2ef [ 36.912690] panic+0x26a/0x50e [ 36.915868] ? __warn_printk+0xf3/0xf3 [ 36.919748] ? refcount_dec_not_one+0x1bc/0x1d0 [ 36.924411] ? __probe_kernel_read+0x130/0x1b0 [ 36.929070] ? __warn.cold+0x5/0x5a [ 36.932682] ? __warn+0xe4/0x200 [ 36.936036] ? refcount_dec_not_one+0x1bc/0x1d0 [ 36.940701] __warn.cold+0x20/0x5a [ 36.944329] ? refcount_dec_not_one+0x1bc/0x1d0 [ 36.949000] report_bug+0x262/0x2b0 [ 36.952635] do_error_trap+0x1d7/0x310 [ 36.956518] ? math_error+0x310/0x310 [ 36.960308] ? __irq_work_queue_local+0x101/0x160 [ 36.965176] ? irq_work_queue+0x29/0x80 [ 36.969151] ? error_entry+0x72/0xd0 [ 36.972857] ? trace_hardirqs_off_caller+0x6e/0x210 [ 36.977865] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 36.982713] invalid_op+0x14/0x20 [ 36.986162] RIP: 0010:refcount_dec_not_one+0x1bc/0x1d0 [ 36.991460] Code: 1d d5 96 98 07 31 ff 89 de e8 f0 71 ec fd 84 db 75 89 e8 b7 70 ec fd 48 c7 c7 e0 c0 b3 88 c6 05 b5 96 98 07 01 e8 89 a8 7c 04 <0f> 0b 41 bc 01 00 00 00 e9 6a ff ff ff e8 22 91 c1 fd 66 90 41 54 [ 37.010359] RSP: 0018:ffff8880af76fbd0 EFLAGS: 00010282 [ 37.015718] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 37.023015] RDX: 0000000000000000 RSI: ffffffff814dff01 RDI: ffffed1015eedf6c [ 37.030280] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 [ 37.037547] R10: 0000000000000005 R11: 0000000000000000 R12: 00000000ffffffff [ 37.044824] R13: 1ffff11015eedf7b R14: ffff8880af76fbf8 R15: ffff8880a9470868 [ 37.052098] ? vprintk_func+0x81/0x180 [ 37.055981] ? __mutex_unlock_slowpath+0x2be/0x610 [ 37.060916] ? refcount_dec_and_test_checked+0x20/0x20 [ 37.066181] ? wait_for_completion_io+0x10/0x10 [ 37.070858] refcount_dec_and_mutex_lock+0x1c/0x80 [ 37.075780] nbd_config_put+0x5bb/0x870 [ 37.079744] nbd_release+0xf4/0x170 [ 37.083358] ? nbd_queue_rq+0xe60/0xe60 [ 37.087316] __blkdev_put+0x636/0x870 [ 37.091104] ? fsync_bdev+0xc0/0xc0 [ 37.094717] ? locks_remove_file+0x2cd/0x450 [ 37.099139] ? blkdev_put+0x85/0x520 [ 37.102865] ? blkdev_put+0x520/0x520 [ 37.106662] blkdev_close+0x86/0xb0 [ 37.110284] __fput+0x2ce/0x890 [ 37.113560] task_work_run+0x148/0x1c0 [ 37.117451] exit_to_usermode_loop+0x251/0x2a0 [ 37.122023] do_syscall_64+0x538/0x620 [ 37.125903] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 37.131080] RIP: 0033:0x7fab95d3a270 [ 37.134799] Code: 73 01 c3 48 8b 0d 38 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c1 20 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24 [ 37.153905] RSP: 002b:00007ffd4343bc18 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 [ 37.161608] RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fab95d3a270 [ 37.168895] RDX: 000000000aba9500 RSI: 0000000000000000 RDI: 0000000000000007 [ 37.176345] RBP: 00007fab96bf4710 R08: 0000000000000045 R09: 0000000000000018 [ 37.183608] R10: 000055ca705ee1b8 R11: 0000000000000246 R12: 0000000000000000 [ 37.190866] R13: 000055ca705e96e0 R14: 0000000000000003 R15: 000000000000000e [ 37.198549] Kernel Offset: disabled [ 37.202212] Rebooting in 86400 seconds..