[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 66.220978][ T28] audit: type=1800 audit(1576341347.412:25): pid=8765 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 66.242942][ T28] audit: type=1800 audit(1576341347.412:26): pid=8765 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 66.299180][ T28] audit: type=1800 audit(1576341347.412:27): pid=8765 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.194' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 75.810742][ T8916] ------------[ cut here ]------------ [ 75.816416][ T8916] refcount_t: underflow; use-after-free. [ 75.822581][ T8916] WARNING: CPU: 1 PID: 8916 at lib/refcount.c:28 refcount_warn_saturate+0x1dc/0x1f0 [ 75.831971][ T8916] Kernel panic - not syncing: panic_on_warn set ... [ 75.838539][ T8916] CPU: 1 PID: 8916 Comm: syz-executor619 Not tainted 5.5.0-rc1-next-20191213-syzkaller #0 [ 75.848400][ T8916] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 75.858623][ T8916] Call Trace: [ 75.861906][ T8916] dump_stack+0x197/0x210 [ 75.866230][ T8916] ? refcount_warn_saturate+0x140/0x1f0 [ 75.871766][ T8916] panic+0x2e3/0x75c [ 75.875645][ T8916] ? add_taint.cold+0x16/0x16 [ 75.880323][ T8916] ? __kasan_check_write+0x14/0x20 [ 75.885422][ T8916] ? __warn.cold+0x14/0x3e [ 75.889817][ T8916] ? __warn+0xd9/0x1cf [ 75.893884][ T8916] ? refcount_warn_saturate+0x1dc/0x1f0 [ 75.899413][ T8916] __warn.cold+0x2f/0x3e [ 75.903661][ T8916] ? refcount_warn_saturate+0x1dc/0x1f0 [ 75.909228][ T8916] report_bug+0x289/0x300 [ 75.913598][ T8916] do_error_trap+0x11b/0x200 [ 75.918193][ T8916] do_invalid_op+0x37/0x50 [ 75.922730][ T8916] ? refcount_warn_saturate+0x1dc/0x1f0 [ 75.928260][ T8916] invalid_op+0x23/0x30 [ 75.932415][ T8916] RIP: 0010:refcount_warn_saturate+0x1dc/0x1f0 [ 75.938549][ T8916] Code: e9 d8 fe ff ff 48 89 df e8 41 31 23 fe e9 85 fe ff ff e8 a7 4e e5 fd 48 c7 c7 20 d8 6f 88 c6 05 75 96 ec 06 01 e8 73 de b5 fd <0f> 0b e9 ac fe ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 [ 75.958151][ T8916] RSP: 0018:ffffc900025875d0 EFLAGS: 00010282 [ 75.964217][ T8916] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 75.972173][ T8916] RDX: 0000000000000000 RSI: ffffffff815e8b66 RDI: fffff520004b0eac [ 75.980130][ T8916] RBP: ffffc900025875e0 R08: ffff8880a959a2c0 R09: fffffbfff165a7ba [ 75.988095][ T8916] R10: fffffbfff165a7b9 R11: ffffffff8b2d3dcf R12: 0000000000000003 [ 75.996053][ T8916] R13: ffff88809339ba04 R14: 0000000000000900 R15: ffff8880a35ae7c0 [ 76.004024][ T8916] ? vprintk_func+0x86/0x189 [ 76.008616][ T8916] sock_wfree+0x1f8/0x260 [ 76.012944][ T8916] sctp_wfree+0x389/0x990 [ 76.017262][ T8916] ? __sctp_write_space+0x5d0/0x5d0 [ 76.022589][ T8916] skb_release_head_state+0xeb/0x260 [ 76.027869][ T8916] skb_release_all+0x16/0x60 [ 76.032453][ T8916] consume_skb+0xfb/0x410 [ 76.036775][ T8916] sctp_chunk_put+0x1d4/0x2f0 [ 76.041435][ T8916] sctp_chunk_free+0x56/0x70 [ 76.046007][ T8916] __sctp_outq_teardown+0x1d0/0xc60 [ 76.051191][ T8916] sctp_outq_free+0x16/0x20 [ 76.055689][ T8916] sctp_association_free+0x208/0x7e0 [ 76.060969][ T8916] sctp_do_sm+0x3a4a/0x5160 [ 76.065474][ T8916] ? __kmalloc_node_track_caller+0x3d/0x70 [ 76.071267][ T8916] ? sctp_do_8_2_transport_strike.isra.0+0xa80/0xa80 [ 76.077932][ T8916] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 76.084068][ T8916] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 76.090116][ T8916] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 76.096080][ T8916] ? __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 76.101879][ T8916] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 76.107601][ T8916] ? sctp_init_cause+0x1ae/0x230 [ 76.112685][ T8916] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 76.118394][ T8916] ? skb_put+0x177/0x1d0 [ 76.122623][ T8916] ? memcpy+0x46/0x50 [ 76.126591][ T8916] sctp_primitive_ABORT+0xa0/0xd0 [ 76.131604][ T8916] sctp_close+0x259/0x960 [ 76.136079][ T8916] ? sctp_accept+0x710/0x710 [ 76.140765][ T8916] ? __kasan_check_write+0x14/0x20 [ 76.145876][ T8916] ? down_write+0xdf/0x150 [ 76.150285][ T8916] ? ip_mc_drop_socket+0x211/0x270 [ 76.155390][ T8916] inet_release+0xed/0x200 [ 76.159817][ T8916] __sock_release+0xce/0x280 [ 76.164481][ T8916] sock_close+0x1e/0x30 [ 76.168639][ T8916] __fput+0x2ff/0x890 [ 76.172605][ T8916] ? __sock_release+0x280/0x280 [ 76.177450][ T8916] ____fput+0x16/0x20 [ 76.181422][ T8916] task_work_run+0x145/0x1c0 [ 76.186000][ T8916] do_exit+0x909/0x2f20 [ 76.190147][ T8916] ? sock_common_getsockopt+0x94/0xd0 [ 76.195503][ T8916] ? mm_update_next_owner+0x7c0/0x7c0 [ 76.200852][ T8916] ? __sys_getsockopt+0x1b2/0x310 [ 76.205866][ T8916] ? kernel_accept+0x310/0x310 [ 76.210608][ T8916] ? handle_mm_fault+0x4ab/0xa50 [ 76.215553][ T8916] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 76.221017][ T8916] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 76.226462][ T8916] do_group_exit+0x135/0x360 [ 76.231044][ T8916] __x64_sys_exit_group+0x44/0x50 [ 76.236059][ T8916] do_syscall_64+0xfa/0x790 [ 76.240547][ T8916] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.246477][ T8916] RIP: 0033:0x43ef98 [ 76.250358][ T8916] Code: Bad RIP value. [ 76.254442][ T8916] RSP: 002b:00007ffd5b28f778 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 76.262856][ T8916] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ef98 [ 76.270841][ T8916] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 76.278969][ T8916] RBP: 00000000004be7a8 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 76.286923][ T8916] R10: 000000002059aff8 R11: 0000000000000246 R12: 0000000000000001 [ 76.294878][ T8916] R13: 00000000006d01a0 R14: 0000000000000000 R15: 0000000000000000 [ 76.304394][ T8916] Kernel Offset: disabled [ 76.308795][ T8916] Rebooting in 86400 seconds..