[ 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 '10.128.1.2' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 58.203869][ T7173] IPVS: ftp: loaded support on port[0] = 21 [ 58.238830][ T7173] netlink: 16 bytes leftover after parsing attributes in process `syz-executor145'. [ 58.295787][ T7173] ------------[ cut here ]------------ [ 58.301281][ T7173] refcount_t: underflow; use-after-free. [ 58.308313][ T7173] WARNING: CPU: 1 PID: 7173 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 58.317711][ T7173] Kernel panic - not syncing: panic_on_warn set ... [ 58.324272][ T7173] CPU: 1 PID: 7173 Comm: syz-executor145 Not tainted 5.6.0-rc7-syzkaller #0 [ 58.332912][ T7173] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 58.342979][ T7173] Call Trace: [ 58.346250][ T7173] dump_stack+0x188/0x20d [ 58.350559][ T7173] ? refcount_warn_saturate+0x190/0x1e0 [ 58.356186][ T7173] panic+0x2e3/0x75c [ 58.360066][ T7173] ? add_taint.cold+0x16/0x16 [ 58.364726][ T7173] ? __probe_kernel_read+0x188/0x1d0 [ 58.369987][ T7173] ? __warn.cold+0x14/0x35 [ 58.374376][ T7173] ? __warn+0xd5/0x1c8 [ 58.378442][ T7173] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.383978][ T7173] __warn.cold+0x2f/0x35 [ 58.388226][ T7173] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.393761][ T7173] report_bug+0x27b/0x2f0 [ 58.398076][ T7173] do_error_trap+0x12b/0x220 [ 58.402640][ T7173] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.408175][ T7173] do_invalid_op+0x32/0x40 [ 58.412568][ T7173] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.418105][ T7173] invalid_op+0x23/0x30 [ 58.422242][ T7173] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 58.428371][ T7173] Code: e9 db fe ff ff 48 89 df e8 4c 63 1f fe e9 8a fe ff ff e8 f2 99 e2 fd 48 c7 c7 00 a9 51 88 c6 05 c6 a0 d1 06 01 e8 d7 aa b4 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 58.447957][ T7173] RSP: 0018:ffffc900017a7d38 EFLAGS: 00010286 [ 58.454003][ T7173] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 58.461965][ T7173] RDX: 0000000000000000 RSI: ffffffff815c06c1 RDI: fffff520002f4f99 [ 58.469920][ T7173] RBP: 0000000000000003 R08: ffff88808e26a080 R09: ffffed1015ce6659 [ 58.477890][ T7173] R10: ffffed1015ce6658 R11: ffff8880ae7332c7 R12: ffff888095f22040 [ 58.485883][ T7173] R13: ffff888095f22044 R14: 00000000000002aa R15: ffff88809f3d1540 [ 58.493854][ T7173] ? vprintk_func+0x81/0x17e [ 58.498430][ T7173] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.503952][ T7173] free_nsproxy+0x445/0x4a0 [ 58.508437][ T7173] switch_task_namespaces+0xaa/0xc0 [ 58.513639][ T7173] do_exit+0xb2f/0x2dd0 [ 58.517798][ T7173] ? mm_update_next_owner+0x7a0/0x7a0 [ 58.523201][ T7173] ? up_read+0x1ab/0x750 [ 58.527432][ T7173] ? mark_held_locks+0x9f/0xe0 [ 58.532184][ T7173] ? down_read_non_owner+0x470/0x470 [ 58.537462][ T7173] ? handle_mm_fault+0x491/0xa10 [ 58.542381][ T7173] do_group_exit+0x125/0x340 [ 58.547102][ T7173] __x64_sys_exit_group+0x3a/0x50 [ 58.552145][ T7173] do_syscall_64+0xf6/0x7d0 [ 58.556635][ T7173] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 58.562519][ T7173] RIP: 0033:0x43f998 [ 58.566413][ T7173] Code: Bad RIP value. [ 58.570463][ T7173] RSP: 002b:00007fffa0be6a28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 58.578863][ T7173] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 58.586847][ T7173] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 58.594839][ T7173] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 58.602791][ T7173] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 58.610742][ T7173] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 58.620147][ T7173] Kernel Offset: disabled [ 58.624558][ T7173] Rebooting in 86400 seconds..