[ OK ] Started Getty on tty4. [ OK ] Started Getty on tty3. [ OK ] Started Getty on tty2. [ OK ] Started Serial Getty on ttyS0. [ OK ] Started Getty on tty1. [ 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. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.221' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 63.869945][ T7055] IPVS: ftp: loaded support on port[0] = 21 [ 63.907365][ T7055] netlink: 16 bytes leftover after parsing attributes in process `syz-executor577'. [ 63.940740][ T7055] ------------[ cut here ]------------ [ 63.946362][ T7055] refcount_t: underflow; use-after-free. [ 63.953043][ T7055] WARNING: CPU: 0 PID: 7055 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 63.962398][ T7055] Kernel panic - not syncing: panic_on_warn set ... [ 63.968961][ T7055] CPU: 0 PID: 7055 Comm: syz-executor577 Not tainted 5.6.0-next-20200406-syzkaller #0 [ 63.978481][ T7055] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 63.988643][ T7055] Call Trace: [ 63.991949][ T7055] dump_stack+0x188/0x20d [ 63.996286][ T7055] ? refcount_warn_saturate+0x190/0x1e0 [ 64.001842][ T7055] panic+0x2e3/0x75c [ 64.005863][ T7055] ? add_taint.cold+0x16/0x16 [ 64.010551][ T7055] ? __probe_kernel_read+0x188/0x1d0 [ 64.015837][ T7055] ? __warn.cold+0x14/0x35 [ 64.020259][ T7055] ? __warn+0xd5/0x1c8 [ 64.024337][ T7055] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.029880][ T7055] __warn.cold+0x2f/0x35 [ 64.034130][ T7055] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.039676][ T7055] report_bug+0x27b/0x2f0 [ 64.044011][ T7055] do_error_trap+0x12b/0x220 [ 64.048613][ T7055] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.054165][ T7055] do_invalid_op+0x32/0x40 [ 64.058575][ T7055] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.064107][ T7055] invalid_op+0x23/0x30 [ 64.068244][ T7055] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 64.074377][ T7055] Code: e9 db fe ff ff 48 89 df e8 3c 62 1a fe e9 8a fe ff ff e8 a2 58 dc fd 48 c7 c7 00 63 72 88 c6 05 1b 8b ed 06 01 e8 27 8b ad fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 64.094082][ T7055] RSP: 0018:ffffc90005737d38 EFLAGS: 00010286 [ 64.100125][ T7055] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 64.108077][ T7055] RDX: 0000000000000000 RSI: ffffffff815ce441 RDI: fffff52000ae6f99 [ 64.116028][ T7055] RBP: 0000000000000003 R08: ffff8880a93ea040 R09: ffffed1015cc66b1 [ 64.123979][ T7055] R10: ffff8880ae633587 R11: ffffed1015cc66b0 R12: ffff8880a852c040 [ 64.131929][ T7055] R13: ffff8880a852c044 R14: 00000000000002aa R15: ffff88809e671000 [ 64.139898][ T7055] ? vprintk_func+0x81/0x17e [ 64.144484][ T7055] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.150018][ T7055] free_nsproxy+0x445/0x4a0 [ 64.154501][ T7055] switch_task_namespaces+0xaa/0xc0 [ 64.159680][ T7055] do_exit+0xb4e/0x2e10 [ 64.163819][ T7055] ? mm_update_next_owner+0x7a0/0x7a0 [ 64.169163][ T7055] ? up_read+0x1a8/0x750 [ 64.173389][ T7055] ? down_read_nested+0x430/0x430 [ 64.178396][ T7055] ? handle_mm_fault+0x29e/0x660 [ 64.183313][ T7055] do_group_exit+0x125/0x340 [ 64.187884][ T7055] __x64_sys_exit_group+0x3a/0x50 [ 64.193178][ T7055] do_syscall_64+0xf6/0x7d0 [ 64.197676][ T7055] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 64.203555][ T7055] RIP: 0033:0x43f998 [ 64.207448][ T7055] Code: Bad RIP value. [ 64.211499][ T7055] RSP: 002b:00007ffe049a1a48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 64.219898][ T7055] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 64.227904][ T7055] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 64.235869][ T7055] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 64.243917][ T7055] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 64.251872][ T7055] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 64.261027][ T7055] Kernel Offset: disabled [ 64.265406][ T7055] Rebooting in 86400 seconds..