[ 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 '10.128.1.47' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 64.492250][ T7195] IPVS: ftp: loaded support on port[0] = 21 [ 64.533915][ T7195] netlink: 16 bytes leftover after parsing attributes in process `syz-executor227'. [ 64.589952][ T7195] ------------[ cut here ]------------ [ 64.595469][ T7195] refcount_t: underflow; use-after-free. [ 64.602031][ T7195] WARNING: CPU: 0 PID: 7195 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 64.611429][ T7195] Kernel panic - not syncing: panic_on_warn set ... [ 64.618025][ T7195] CPU: 0 PID: 7195 Comm: syz-executor227 Not tainted 5.6.0-next-20200408-syzkaller #0 [ 64.627655][ T7195] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 64.637703][ T7195] Call Trace: [ 64.640983][ T7195] dump_stack+0x188/0x20d [ 64.645299][ T7195] ? refcount_warn_saturate+0xe0/0x1e0 [ 64.650742][ T7195] panic+0x2e3/0x75c [ 64.654636][ T7195] ? add_taint.cold+0x16/0x16 [ 64.659302][ T7195] ? __probe_kernel_read+0x188/0x1d0 [ 64.664574][ T7195] ? __warn.cold+0x14/0x35 [ 64.669146][ T7195] ? __warn+0xd5/0x1c8 [ 64.673202][ T7195] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.678747][ T7195] __warn.cold+0x2f/0x35 [ 64.682974][ T7195] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.688523][ T7195] report_bug+0x27b/0x2f0 [ 64.692861][ T7195] do_error_trap+0x12b/0x220 [ 64.697431][ T7195] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.703672][ T7195] do_invalid_op+0x32/0x40 [ 64.708071][ T7195] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.713636][ T7195] invalid_op+0x23/0x30 [ 64.717775][ T7195] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 64.723909][ T7195] Code: e9 db fe ff ff 48 89 df e8 8c 5f 1a fe e9 8a fe ff ff e8 f2 55 dc fd 48 c7 c7 40 66 72 88 c6 05 6d a9 ed 06 01 e8 77 88 ad fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 64.743858][ T7195] RSP: 0018:ffffc900054e7d38 EFLAGS: 00010286 [ 64.750166][ T7195] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 64.758203][ T7195] RDX: 0000000000000000 RSI: ffffffff815cd441 RDI: fffff52000a9cf99 [ 64.766159][ T7195] RBP: 0000000000000003 R08: ffff8880944d02c0 R09: ffffed1015cc66b1 [ 64.774110][ T7195] R10: ffff8880ae633587 R11: ffffed1015cc66b0 R12: ffff888094aa0040 [ 64.782064][ T7195] R13: ffff888094aa0044 R14: 00000000000002ab R15: ffff888099d08980 [ 64.790089][ T7195] ? vprintk_func+0x81/0x17e [ 64.794687][ T7195] ? refcount_warn_saturate+0x1d1/0x1e0 [ 64.800220][ T7195] free_nsproxy+0x445/0x4a0 [ 64.804706][ T7195] switch_task_namespaces+0xaa/0xc0 [ 64.809922][ T7195] do_exit+0xb4e/0x2e10 [ 64.814072][ T7195] ? mm_update_next_owner+0x7a0/0x7a0 [ 64.819445][ T7195] ? up_read+0x1a8/0x750 [ 64.823666][ T7195] ? down_read_nested+0x430/0x430 [ 64.828675][ T7195] ? handle_mm_fault+0x29e/0x660 [ 64.833591][ T7195] do_group_exit+0x125/0x340 [ 64.838159][ T7195] __x64_sys_exit_group+0x3a/0x50 [ 64.843165][ T7195] do_syscall_64+0xf6/0x7d0 [ 64.847652][ T7195] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 64.853894][ T7195] RIP: 0033:0x43f998 [ 64.857803][ T7195] Code: Bad RIP value. [ 64.861863][ T7195] RSP: 002b:00007ffe8e27ee48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 64.870268][ T7195] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 64.878230][ T7195] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 64.886354][ T7195] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 64.894304][ T7195] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 64.902255][ T7195] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 64.911741][ T7195] Kernel Offset: disabled [ 64.916137][ T7195] Rebooting in 86400 seconds..