[ 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 '10.128.10.38' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 58.415411][ T7037] IPVS: ftp: loaded support on port[0] = 21 [ 58.452685][ T7037] netlink: 16 bytes leftover after parsing attributes in process `syz-executor731'. [ 58.499810][ T7037] ------------[ cut here ]------------ [ 58.505313][ T7037] refcount_t: underflow; use-after-free. [ 58.511969][ T7037] WARNING: CPU: 0 PID: 7037 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 58.521330][ T7037] Kernel panic - not syncing: panic_on_warn set ... [ 58.527894][ T7037] CPU: 0 PID: 7037 Comm: syz-executor731 Not tainted 5.6.0-rc7-syzkaller #0 [ 58.536544][ T7037] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 58.546631][ T7037] Call Trace: [ 58.549917][ T7037] dump_stack+0x188/0x20d [ 58.554238][ T7037] ? refcount_warn_saturate+0x1b0/0x1e0 [ 58.559779][ T7037] panic+0x2e3/0x75c [ 58.563662][ T7037] ? add_taint.cold+0x16/0x16 [ 58.568342][ T7037] ? __probe_kernel_read+0x188/0x1d0 [ 58.573624][ T7037] ? __warn.cold+0x14/0x35 [ 58.578040][ T7037] ? __warn+0xd5/0x1c8 [ 58.582103][ T7037] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.587661][ T7037] __warn.cold+0x2f/0x35 [ 58.591897][ T7037] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.597452][ T7037] report_bug+0x27b/0x2f0 [ 58.601812][ T7037] do_error_trap+0x12b/0x220 [ 58.606393][ T7037] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.611966][ T7037] do_invalid_op+0x32/0x40 [ 58.616367][ T7037] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.621939][ T7037] invalid_op+0x23/0x30 [ 58.626076][ T7037] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 58.632207][ T7037] Code: e9 db fe ff ff 48 89 df e8 6c 64 1f fe e9 8a fe ff ff e8 12 9b e2 fd 48 c7 c7 00 a9 51 88 c6 05 a6 a1 d1 06 01 e8 f7 ab b4 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 58.651790][ T7037] RSP: 0018:ffffc900020c7d38 EFLAGS: 00010286 [ 58.657827][ T7037] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 58.665782][ T7037] RDX: 0000000000000000 RSI: ffffffff815c06c1 RDI: fffff52000418f99 [ 58.673730][ T7037] RBP: 0000000000000003 R08: ffff8880a12805c0 R09: ffffed1015cc6659 [ 58.681687][ T7037] R10: ffffed1015cc6658 R11: ffff8880ae6332c7 R12: ffff888090fb0040 [ 58.689636][ T7037] R13: ffff888090fb0044 R14: 00000000000002ab R15: ffff8880956b3280 [ 58.697608][ T7037] ? vprintk_func+0x81/0x17e [ 58.702198][ T7037] ? refcount_warn_saturate+0x1d1/0x1e0 [ 58.707721][ T7037] free_nsproxy+0x445/0x4a0 [ 58.712203][ T7037] switch_task_namespaces+0xaa/0xc0 [ 58.717381][ T7037] do_exit+0xb2f/0x2dd0 [ 58.721522][ T7037] ? mm_update_next_owner+0x7a0/0x7a0 [ 58.726870][ T7037] ? up_read+0x1ab/0x750 [ 58.731090][ T7037] ? mark_held_locks+0x9f/0xe0 [ 58.735840][ T7037] ? down_read_non_owner+0x470/0x470 [ 58.741107][ T7037] ? handle_mm_fault+0x491/0xa10 [ 58.746040][ T7037] do_group_exit+0x125/0x340 [ 58.750610][ T7037] __x64_sys_exit_group+0x3a/0x50 [ 58.755611][ T7037] do_syscall_64+0xf6/0x7d0 [ 58.760106][ T7037] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 58.765981][ T7037] RIP: 0033:0x43f998 [ 58.769859][ T7037] Code: Bad RIP value. [ 58.773909][ T7037] RSP: 002b:00007ffd426357b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 58.782293][ T7037] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 58.790244][ T7037] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 58.798207][ T7037] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 58.806163][ T7037] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 58.814157][ T7037] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 58.823375][ T7037] Kernel Offset: disabled [ 58.827755][ T7037] Rebooting in 86400 seconds..