[ 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 '10.128.1.54' (ECDSA) to the list of known hosts. syzkaller login: [ 125.884179][ T6853] 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 [ 127.351534][ T1543] ------------[ cut here ]------------ [ 127.357167][ T1543] refcount_t: addition on 0; use-after-free. [ 127.363614][ T1543] WARNING: CPU: 0 PID: 1543 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 [ 127.373074][ T1543] Kernel panic - not syncing: panic_on_warn set ... [ 127.379679][ T1543] CPU: 0 PID: 1543 Comm: kworker/u5:0 Not tainted 5.8.0-rc7-next-20200731-syzkaller #0 [ 127.389513][ T1543] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 127.399614][ T1543] Workqueue: hci0 hci_rx_work [ 127.404306][ T1543] Call Trace: [ 127.407618][ T1543] dump_stack+0x18f/0x20d [ 127.411976][ T1543] panic+0x2e3/0x75c [ 127.415877][ T1543] ? __warn_printk+0xf3/0xf3 [ 127.420595][ T1543] ? __warn.cold+0x5/0x4a [ 127.424957][ T1543] ? __warn+0xd6/0x1f2 [ 127.429029][ T1543] ? refcount_warn_saturate+0x169/0x1e0 [ 127.435616][ T1543] __warn.cold+0x20/0x4a [ 127.439883][ T1543] ? refcount_warn_saturate+0x169/0x1e0 [ 127.445539][ T1543] report_bug+0x1bd/0x210 [ 127.449893][ T1543] handle_bug+0x38/0x90 [ 127.454051][ T1543] exc_invalid_op+0x14/0x40 [ 127.458554][ T1543] asm_exc_invalid_op+0x12/0x20 [ 127.463408][ T1543] RIP: 0010:refcount_warn_saturate+0x169/0x1e0 [ 127.469577][ T1543] Code: 07 31 ff 89 de e8 67 f4 d8 fd 84 db 0f 85 36 ff ff ff e8 1a f8 d8 fd 48 c7 c7 20 ca 93 88 c6 05 e3 6e 19 07 01 e8 a9 e7 a9 fd <0f> 0b e9 17 ff ff ff e8 fb f7 d8 fd 0f b6 1d c8 6e 19 07 31 ff 89 [ 127.489325][ T1543] RSP: 0018:ffffc90005767908 EFLAGS: 00010286 [ 127.495426][ T1543] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 127.503556][ T1543] RDX: ffff8880a4a96200 RSI: ffffffff815d86e7 RDI: fffff52000aecf13 [ 127.511739][ T1543] RBP: 0000000000000002 R08: 0000000000000001 R09: ffff8880ae6318a7 [ 127.519728][ T1543] R10: 0000000000000000 R11: 746e756f63666572 R12: dffffc0000000000 [ 127.527733][ T1543] R13: 0000000000000001 R14: ffff888093464000 R15: 0000000000000003 [ 127.535748][ T1543] ? vprintk_func+0x97/0x1a6 [ 127.540357][ T1543] ? refcount_warn_saturate+0x169/0x1e0 [ 127.545927][ T1543] l2cap_global_chan_by_psm+0x53f/0x5b0 [ 127.551484][ T1543] ? l2cap_chan_timeout+0x450/0x450 [ 127.557667][ T1543] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 127.563863][ T1543] ? mark_lock+0xbc/0x1710 [ 127.568307][ T1543] ? __lock_acquire+0x16cb/0x5640 [ 127.573356][ T1543] l2cap_recv_frame+0xc3b/0xae10 [ 127.578337][ T1543] ? hci_rx_work+0x35b/0xb50 [ 127.582945][ T1543] ? __lock_acquire+0xbb5/0x5640 [ 127.588008][ T1543] ? l2cap_config_rsp.isra.0+0x1130/0x1130 [ 127.593831][ T1543] ? find_held_lock+0x2d/0x110 [ 127.598613][ T1543] ? hci_rx_work+0x498/0xb50 [ 127.603257][ T1543] ? lock_downgrade+0x830/0x830 [ 127.608127][ T1543] ? lock_acquire+0x1f1/0xad0 [ 127.613109][ T1543] ? hci_rx_work+0x33d/0xb50 [ 127.617804][ T1543] ? find_held_lock+0x2d/0x110 [ 127.622587][ T1543] ? __mutex_unlock_slowpath+0xe2/0x610 [ 127.628587][ T1543] ? hci_conn_enter_active_mode+0x11a/0x2e0 [ 127.634498][ T1543] l2cap_recv_acldata+0x7f6/0x8e0 [ 127.639532][ T1543] hci_rx_work+0x4c7/0xb50 [ 127.643983][ T1543] process_one_work+0x94c/0x1670 [ 127.649927][ T1543] ? lock_release+0x8e0/0x8e0 [ 127.654638][ T1543] ? pwq_dec_nr_in_flight+0x2d0/0x2d0 [ 127.662044][ T1543] ? rwlock_bug.part.0+0x90/0x90 [ 127.667070][ T1543] ? lockdep_hardirqs_off+0x7e/0xb0 [ 127.672315][ T1543] worker_thread+0x64c/0x1120 [ 127.677043][ T1543] ? process_one_work+0x1670/0x1670 [ 127.682263][ T1543] kthread+0x3b5/0x4a0 [ 127.686349][ T1543] ? __kthread_bind_mask+0xc0/0xc0 [ 127.691470][ T1543] ? __kthread_bind_mask+0xc0/0xc0 [ 127.696631][ T1543] ret_from_fork+0x1f/0x30 [ 127.702365][ T1543] Kernel Offset: disabled [ 127.706775][ T1543] Rebooting in 86400 seconds..