[ 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. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.10.39' (ECDSA) to the list of known hosts. syzkaller login: [ 81.094317][ T6886] 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 [ 82.319690][ T6911] ------------[ cut here ]------------ [ 82.325987][ T6911] refcount_t: addition on 0; use-after-free. [ 82.332284][ T6911] WARNING: CPU: 0 PID: 6911 at lib/refcount.c:25 refcount_warn_saturate+0x13d/0x1a0 [ 82.341946][ T6911] Kernel panic - not syncing: panic_on_warn set ... [ 82.348985][ T6911] CPU: 0 PID: 6911 Comm: kworker/u5:1 Not tainted 5.8.0-syzkaller #0 [ 82.357124][ T6911] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 82.367609][ T6911] Workqueue: hci0 hci_rx_work [ 82.372274][ T6911] Call Trace: [ 82.376364][ T6911] dump_stack+0x1f0/0x31e [ 82.382665][ T6911] panic+0x264/0x7a0 [ 82.388671][ T6911] ? __warn+0x102/0x250 [ 82.392837][ T6911] ? refcount_warn_saturate+0x13d/0x1a0 [ 82.398385][ T6911] ? refcount_warn_saturate+0x13d/0x1a0 [ 82.406277][ T6911] __warn+0x227/0x250 [ 82.410270][ T6911] ? refcount_warn_saturate+0x13d/0x1a0 [ 82.415829][ T6911] report_bug+0x1b1/0x2e0 [ 82.420163][ T6911] handle_bug+0x42/0x80 [ 82.424315][ T6911] exc_invalid_op+0x16/0x40 [ 82.428824][ T6911] asm_exc_invalid_op+0x12/0x20 [ 82.433687][ T6911] RIP: 0010:refcount_warn_saturate+0x13d/0x1a0 [ 82.439921][ T6911] Code: c7 c3 ca 14 89 31 c0 e8 41 c0 a9 fd 0f 0b eb a3 e8 f8 0a d8 fd c6 05 38 a8 ec 05 01 48 c7 c7 fa ca 14 89 31 c0 e8 23 c0 a9 fd <0f> 0b eb 85 e8 da 0a d8 fd c6 05 1b a8 ec 05 01 48 c7 c7 26 cb 14 [ 82.459614][ T6911] RSP: 0018:ffffc90001077a70 EFLAGS: 00010246 [ 82.467488][ T6911] RAX: 538ebfb4abbeef00 RBX: 0000000000000002 RCX: ffff8880a7c78380 [ 82.475988][ T6911] RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000 [ 82.484079][ T6911] RBP: 0000000000000002 R08: ffffffff815e07c9 R09: ffffed1015d062c0 [ 82.492057][ T6911] R10: ffffed1015d062c0 R11: 0000000000000000 R12: 0000000000000000 [ 82.500021][ T6911] R13: 0000000000000000 R14: ffff8880a2041018 R15: 0000000000000001 [ 82.508426][ T6911] ? vprintk_emit+0x339/0x3c0 [ 82.513814][ T6911] l2cap_global_chan_by_psm+0x4aa/0x4e0 [ 82.519382][ T6911] l2cap_recv_frame+0x530/0x8f10 [ 82.524329][ T6911] ? hci_rx_work+0x7ae/0x9c0 [ 82.528916][ T6911] ? hci_rx_work+0x7ae/0x9c0 [ 82.533488][ T6911] ? l2cap_recv_acldata+0x743/0xf00 [ 82.538687][ T6911] hci_rx_work+0x7d7/0x9c0 [ 82.543625][ T6911] process_one_work+0x789/0xfc0 [ 82.552155][ T6911] worker_thread+0xaa4/0x1460 [ 82.556939][ T6911] kthread+0x37e/0x3a0 [ 82.563539][ T6911] ? rcu_lock_release+0x20/0x20 [ 82.568376][ T6911] ? kthread_blkcg+0xd0/0xd0 [ 82.572965][ T6911] ret_from_fork+0x1f/0x30 [ 82.579248][ T6911] Kernel Offset: disabled [ 82.584782][ T6911] Rebooting in 86400 seconds..