[ OK ] Started Getty on tty4. [ OK ] Started Getty on tty3. [ OK ] Started Getty on tty2. [ OK ] Started Getty on tty1. [ OK ] Started Serial Getty on ttyS0. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ 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 '10.128.0.63' (ECDSA) to the list of known hosts. syzkaller login: [ 65.016765][ T6875] IPVS: ftp: loaded support on port[0] = 21 [ 65.019087][ T6871] IPVS: ftp: loaded support on port[0] = 21 [ 65.031397][ T6877] IPVS: ftp: loaded support on port[0] = 21 [ 65.034792][ T6878] IPVS: ftp: loaded support on port[0] = 21 [ 65.038920][ T6876] IPVS: ftp: loaded support on port[0] = 21 [ 65.047703][ T6879] IPVS: ftp: loaded support on port[0] = 21 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 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 executing program executing program executing program executing program executing program executing program executing program executing program [ 65.400374][ T23] ------------[ cut here ]------------ [ 65.407633][ T23] refcount_t: underflow; use-after-free. [ 65.434536][ T23] WARNING: CPU: 1 PID: 23 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 executing program executing program executing program executing program executing program executing program [ 65.477618][ T23] Kernel panic - not syncing: panic_on_warn set ... [ 65.484508][ T23] CPU: 1 PID: 23 Comm: kworker/1:1 Not tainted 5.8.0-syzkaller #0 [ 65.493024][ T23] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 65.503186][ T23] Workqueue: events do_enable_set [ 65.508251][ T23] Call Trace: [ 65.511599][ T23] dump_stack+0x18f/0x20d [ 65.516048][ T23] panic+0x2e3/0x75c [ 65.520158][ T23] ? __warn_printk+0xf3/0xf3 executing program executing program executing program [ 65.525032][ T23] ? __warn.cold+0x5/0x45 [ 65.529457][ T23] ? __warn+0xd6/0x1f2 [ 65.533918][ T23] ? refcount_warn_saturate+0x1d1/0x1e0 [ 65.539756][ T23] __warn.cold+0x20/0x45 [ 65.544431][ T23] ? refcount_warn_saturate+0x1d1/0x1e0 [ 65.550349][ T23] report_bug+0x1bd/0x210 [ 65.555659][ T23] handle_bug+0x38/0x90 [ 65.560011][ T23] ? __warn_printk+0xc6/0xf3 [ 65.565342][ T23] exc_invalid_op+0x14/0x40 [ 65.570173][ T23] asm_exc_invalid_op+0x12/0x20 [ 65.576477][ T23] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 65.585260][ T23] Code: e9 db fe ff ff 48 89 df e8 3c 86 1b fe e9 8a fe ff ff e8 72 fe db fd 48 c7 c7 20 6c 93 88 c6 05 c1 8c 12 07 01 e8 d1 0f ad fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 65.607409][ T23] RSP: 0018:ffffc90000df7bd0 EFLAGS: 00010282 [ 65.614090][ T23] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 65.622602][ T23] RDX: ffff8880a97f8000 RSI: ffffffff815d8ea7 RDI: fffff520001bef6c [ 65.631205][ T23] RBP: 0000000000000003 R08: 0000000000000001 R09: ffff8880ae731927 [ 65.639396][ T23] R10: 0000000000000000 R11: 0000000000003254 R12: ffff888097ce1018 [ 65.647642][ T23] R13: ffff88809e31fd10 R14: ffff8880a97ac600 R15: ffff88809e31fd00 [ 65.656075][ T23] ? vprintk_func+0x97/0x1a6 [ 65.660686][ T23] l2cap_chan_put+0x1d3/0x230 [ 65.665580][ T23] do_enable_set+0x4f9/0x980 [ 65.670656][ T23] ? chan_recv_cb+0xa10/0xa10 [ 65.675345][ T23] ? _raw_spin_unlock_irq+0x1f/0x80 [ 65.680825][ T23] ? _raw_spin_unlock_irq+0x1f/0x80 [ 65.686038][ T23] ? lock_is_held_type+0xbb/0xf0 [ 65.691001][ T23] process_one_work+0x94c/0x1670 [ 65.696042][ T23] ? lock_release+0x8e0/0x8e0 [ 65.700738][ T23] ? pwq_dec_nr_in_flight+0x2d0/0x2d0 [ 65.706207][ T23] ? rwlock_bug.part.0+0x90/0x90 [ 65.711163][ T23] worker_thread+0x64c/0x1120 [ 65.715944][ T23] ? process_one_work+0x1670/0x1670 [ 65.721150][ T23] kthread+0x3b5/0x4a0 [ 65.725232][ T23] ? __kthread_bind_mask+0xc0/0xc0 [ 65.730354][ T23] ? __kthread_bind_mask+0xc0/0xc0 [ 65.735490][ T23] ret_from_fork+0x1f/0x30 [ 65.741973][ T23] Kernel Offset: disabled [ 65.746525][ T23] Rebooting in 86400 seconds..