[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 70.239753][ T27] audit: type=1800 audit(1584056155.985:25): pid=9601 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 70.259888][ T27] audit: type=1800 audit(1584056155.995:26): pid=9601 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 70.281619][ T27] audit: type=1800 audit(1584056155.995:27): pid=9601 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 '10.128.0.100' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 81.600038][ T9753] ------------[ cut here ]------------ [ 81.605894][ T9753] refcount_t: underflow; use-after-free. [ 81.612033][ T9753] WARNING: CPU: 0 PID: 9753 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 81.622098][ T9753] Kernel panic - not syncing: panic_on_warn set ... [ 81.628871][ T9753] CPU: 0 PID: 9753 Comm: syz-executor945 Not tainted 5.6.0-rc5-syzkaller #0 [ 81.638309][ T9753] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 81.648538][ T9753] Call Trace: [ 81.651844][ T9753] dump_stack+0x188/0x20d [ 81.656249][ T9753] ? refcount_warn_saturate+0x190/0x1e0 [ 81.662196][ T9753] panic+0x2e3/0x75c [ 81.666130][ T9753] ? add_taint.cold+0x16/0x16 [ 81.670812][ T9753] ? __probe_kernel_read+0x188/0x1d0 [ 81.676081][ T9753] ? __warn.cold+0x14/0x35 [ 81.680539][ T9753] ? __warn+0xd5/0x1c8 [ 81.684778][ T9753] ? refcount_warn_saturate+0x1d1/0x1e0 [ 81.691183][ T9753] __warn.cold+0x2f/0x35 [ 81.695503][ T9753] ? refcount_warn_saturate+0x1d1/0x1e0 [ 81.701397][ T9753] report_bug+0x27b/0x2f0 [ 81.705949][ T9753] do_error_trap+0x12b/0x220 [ 81.710553][ T9753] ? refcount_warn_saturate+0x1d1/0x1e0 [ 81.716246][ T9753] do_invalid_op+0x32/0x40 [ 81.720749][ T9753] ? refcount_warn_saturate+0x1d1/0x1e0 [ 81.726814][ T9753] invalid_op+0x23/0x30 [ 81.731431][ T9753] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 81.737997][ T9753] Code: e9 db fe ff ff 48 89 df e8 9c 10 20 fe e9 8a fe ff ff e8 62 52 e3 fd 48 c7 c7 00 aa 51 88 c6 05 85 68 d2 06 01 e8 d7 62 b5 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 81.759147][ T9753] RSP: 0018:ffffc9000208f698 EFLAGS: 00010286 [ 81.765460][ T9753] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 81.773729][ T9753] RDX: 0000000000000000 RSI: ffffffff815bf511 RDI: fffff52000411ec5 [ 81.781833][ T9753] RBP: 0000000000000003 R08: ffff8880a7cf8140 R09: fffffbfff180e58a [ 81.790061][ T9753] R10: fffffbfff180e589 R11: ffffffff8c072c4f R12: 0000000000008100 [ 81.799264][ T9753] R13: ffff8880a4219a04 R14: ffff8880a2909540 R15: ffff8880a2909580 [ 81.807534][ T9753] ? vprintk_func+0x81/0x17e [ 81.813194][ T9753] ? refcount_warn_saturate+0x1d1/0x1e0 [ 81.819145][ T9753] sock_wfree+0x1e3/0x240 [ 81.823603][ T9753] sctp_wfree+0x372/0x960 [ 81.829349][ T9753] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 81.835440][ T9753] ? __sctp_write_space+0x5c0/0x5c0 [ 81.841165][ T9753] skb_release_head_state+0xe2/0x250 [ 81.847456][ T9753] skb_release_all+0x11/0x60 [ 81.852400][ T9753] consume_skb+0xf3/0x400 [ 81.856809][ T9753] sctp_chunk_put+0x1c0/0x2d0 [ 81.861727][ T9753] __sctp_outq_teardown+0x715/0xc60 [ 81.868409][ T9753] sctp_association_free+0x212/0x7e0 [ 81.874222][ T9753] sctp_do_sm+0x3911/0x4ed0 [ 81.879826][ T9753] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 81.886382][ T9753] ? sctp_do_8_2_transport_strike.isra.0+0xa60/0xa60 [ 81.894072][ T9753] ? kmem_cache_alloc_node_trace+0x3a2/0x790 [ 81.900433][ T9753] ? sctp_chunkify+0x46/0x290 [ 81.905381][ T9753] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 81.911125][ T9753] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 81.917461][ T9753] ? __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 81.923554][ T9753] ? kmem_cache_alloc+0x261/0x730 [ 81.928594][ T9753] ? sctp_addto_chunk+0x290/0x290 [ 81.933885][ T9753] ? skb_put+0x15d/0x1c0 [ 81.938583][ T9753] ? memcpy+0x35/0x50 [ 81.942603][ T9753] sctp_primitive_ABORT+0x9b/0xc0 [ 81.948646][ T9753] sctp_close+0x22e/0x8a0 [ 81.953341][ T9753] ? sctp_accept+0x6a0/0x6a0 [ 81.958411][ T9753] ? down_write+0xdb/0x150 [ 81.962827][ T9753] ? ip_mc_drop_socket+0x16/0x260 [ 81.967874][ T9753] ? __sock_release+0x280/0x280 [ 81.972721][ T9753] inet_release+0xe4/0x1f0 [ 81.977244][ T9753] __sock_release+0xcd/0x280 [ 81.981925][ T9753] sock_close+0x18/0x20 [ 81.986549][ T9753] __fput+0x2da/0x850 [ 81.990651][ T9753] task_work_run+0x13f/0x1b0 [ 81.995673][ T9753] do_exit+0xb34/0x2dd0 [ 81.999947][ T9753] ? mm_update_next_owner+0x7a0/0x7a0 [ 82.006135][ T9753] ? __sys_getsockopt+0x18d/0x2e0 [ 82.011961][ T9753] ? kernel_accept+0x360/0x360 [ 82.017420][ T9753] ? down_read_non_owner+0x470/0x470 [ 82.022962][ T9753] ? handle_mm_fault+0x491/0xa10 [ 82.028366][ T9753] do_group_exit+0x125/0x340 [ 82.033653][ T9753] __x64_sys_exit_group+0x3a/0x50 [ 82.038686][ T9753] do_syscall_64+0xf6/0x7d0 [ 82.043199][ T9753] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 82.049304][ T9753] RIP: 0033:0x43ef98 [ 82.053508][ T9753] Code: Bad RIP value. [ 82.057580][ T9753] RSP: 002b:00007ffdc1072858 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 82.066353][ T9753] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ef98 [ 82.074724][ T9753] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 82.082806][ T9753] RBP: 00000000004be7a8 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 82.090897][ T9753] R10: 000000002059aff8 R11: 0000000000000246 R12: 0000000000000001 [ 82.098966][ T9753] R13: 00000000006d01a0 R14: 0000000000000000 R15: 0000000000000000 [ 82.109698][ T9753] Kernel Offset: disabled [ 82.114298][ T9753] Rebooting in 86400 seconds..