[ 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 '10.128.0.252' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 58.195867][ T7027] IPVS: ftp: loaded support on port[0] = 21 [ 58.234059][ T7027] netlink: 16 bytes leftover after parsing attributes in process `syz-executor555'. [ 58.295813][ T7027] ------------[ cut here ]------------ [ 58.301586][ T7027] refcount_t: underflow; use-after-free. [ 58.307740][ T7027] WARNING: CPU: 0 PID: 7027 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 58.317217][ T7027] Kernel panic - not syncing: panic_on_warn set ... [ 58.324026][ T7027] CPU: 0 PID: 7027 Comm: syz-executor555 Not tainted 5.6.0-syzkaller #0 [ 58.332336][ T7027] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 58.342387][ T7027] Call Trace: [ 58.345669][ T7027] dump_stack+0x188/0x20d [ 58.349981][ T7027] ? refcount_warn_saturate+0x150/0x1e0 [ 58.355733][ T7027] panic+0x2e3/0x75c [ 58.359612][ T7027] ? add_taint.cold+0x16/0x16 [ 58.364297][ T7027] ? __probe_kernel_read+0x188/0x1d0 [ 58.369567][ T7027] ? __warn.cold+0x14/0x35 [ 58.373966][ T7027] ? __warn+0xd5/0x1c8 [ 58.378025][ T7027] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.383553][ T7027] __warn.cold+0x2f/0x35 [ 58.387784][ T7027] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.393309][ T7027] report_bug+0x27b/0x2f0 [ 58.397626][ T7027] do_error_trap+0x12b/0x220 [ 58.402209][ T7027] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.407762][ T7027] do_invalid_op+0x32/0x40 [ 58.412158][ T7027] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.417696][ T7027] invalid_op+0x23/0x30 [ 58.421851][ T7027] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 58.427994][ T7027] Code: e9 db fe ff ff 48 89 df e8 bc 43 1f fe e9 8a fe ff ff e8 f2 6f e2 fd 48 c7 c7 80 a3 51 88 c6 05 f0 3a d2 06 01 e8 77 f8 b3 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 58.447732][ T7027] RSP: 0018:ffffc90002087d38 EFLAGS: 00010286 [ 58.453785][ T7027] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 58.461738][ T7027] RDX: 0000000000000000 RSI: ffffffff815c8561 RDI: fffff52000410f99 [ 58.469693][ T7027] RBP: 0000000000000003 R08: ffff88809671a380 R09: ffffed1015cc6699 [ 58.477658][ T7027] R10: ffffed1015cc6698 R11: ffff8880ae6334c7 R12: ffff888094d9c040 [ 58.485756][ T7027] R13: ffff888094d9c044 R14: 00000000000002ac R15: ffff8880a2ffc1c0 [ 58.493918][ T7027] ? vprintk_func+0x81/0x17e [ 58.498516][ T7027] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.504055][ T7027] free_nsproxy+0x445/0x4a0 [ 58.508566][ T7027] switch_task_namespaces+0xaa/0xc0 [ 58.513752][ T7027] do_exit+0xb2f/0x2dd0 [ 58.517900][ T7027] ? mm_update_next_owner+0x7a0/0x7a0 [ 58.523265][ T7027] ? up_read+0x1ab/0x750 [ 58.527586][ T7027] ? mark_held_locks+0x9f/0xe0 [ 58.532337][ T7027] ? down_read_nested+0x420/0x420 [ 58.537386][ T7027] ? handle_mm_fault+0x491/0xa10 [ 58.542326][ T7027] do_group_exit+0x125/0x340 [ 58.547093][ T7027] __x64_sys_exit_group+0x3a/0x50 [ 58.552109][ T7027] do_syscall_64+0xf6/0x7d0 [ 58.556615][ T7027] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 58.562501][ T7027] RIP: 0033:0x43f9b8 [ 58.566411][ T7027] Code: Bad RIP value. [ 58.570459][ T7027] RSP: 002b:00007fff719ed018 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 58.578866][ T7027] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f9b8 [ 58.586832][ T7027] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 58.594811][ T7027] RBP: 00000000004bfa30 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 58.602780][ T7027] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 58.610747][ T7027] R13: 00000000006d21c0 R14: 0000000000000000 R15: 0000000000000000 [ 58.620374][ T7027] Kernel Offset: disabled [ 58.624769][ T7027] Rebooting in 86400 seconds..