[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 86.436297][ T27] audit: type=1800 audit(1584579217.931:25): pid=9441 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 86.456388][ T27] audit: type=1800 audit(1584579217.931:26): pid=9441 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 86.512951][ T27] audit: type=1800 audit(1584579217.931:27): pid=9441 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.10.15' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program syzkaller login: [ 112.071689][ T9603] ================================================================== [ 112.071755][ T9603] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 112.071766][ T9603] Write of size 8 at addr ffff8880956c8108 by task syz-executor219/9603 [ 112.071769][ T9603] [ 112.071783][ T9603] CPU: 1 PID: 9603 Comm: syz-executor219 Not tainted 5.6.0-rc6-syzkaller #0 [ 112.071791][ T9603] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 112.071796][ T9603] Call Trace: [ 112.071813][ T9603] dump_stack+0x188/0x20d [ 112.071825][ T9603] ? con_shutdown+0x7f/0x90 [ 112.071839][ T9603] ? con_shutdown+0x7f/0x90 [ 112.071858][ T9603] print_address_description.constprop.0.cold+0xd3/0x315 [ 112.071869][ T9603] ? con_shutdown+0x7f/0x90 [ 112.071882][ T9603] ? con_shutdown+0x7f/0x90 [ 112.071894][ T9603] __kasan_report.cold+0x1a/0x32 [ 112.071912][ T9603] ? con_shutdown+0x7f/0x90 [ 112.071929][ T9603] kasan_report+0xe/0x20 [ 112.071941][ T9603] con_shutdown+0x7f/0x90 [ 112.071953][ T9603] ? update_region+0x140/0x140 [ 112.071964][ T9603] release_tty+0xca/0x450 [ 112.071980][ T9603] tty_release_struct+0x37/0x50 [ 112.071994][ T9603] tty_release+0xbc7/0xe90 [ 112.072020][ T9603] ? do_tty_hangup+0x30/0x30 [ 112.072031][ T9603] __fput+0x2da/0x850 [ 112.072061][ T9603] task_work_run+0x13f/0x1b0 [ 112.072084][ T9603] do_exit+0xb34/0x2dd0 [ 112.072117][ T9603] ? mm_update_next_owner+0x7a0/0x7a0 [ 112.072132][ T9603] ? up_read+0x1ab/0x750 [ 112.072146][ T9603] ? mark_held_locks+0x9f/0xe0 [ 112.072162][ T9603] ? down_read_non_owner+0x470/0x470 [ 112.072183][ T9603] ? handle_mm_fault+0x491/0xa10 [ 112.072203][ T9603] do_group_exit+0x125/0x340 [ 112.072221][ T9603] __x64_sys_exit_group+0x3a/0x50 [ 112.072235][ T9603] do_syscall_64+0xf6/0x7d0 [ 112.072253][ T9603] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 112.072263][ T9603] RIP: 0033:0x43ff38 [ 112.072274][ T9603] Code: Bad RIP value. [ 112.072281][ T9603] RSP: 002b:00007ffce62579e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 112.072293][ T9603] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 112.072300][ T9603] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 112.072307][ T9603] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 112.072314][ T9603] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 112.072321][ T9603] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 112.072350][ T9603] [ 112.072356][ T9603] Allocated by task 9603: [ 112.072369][ T9603] save_stack+0x1b/0x80 [ 112.072381][ T9603] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 112.072393][ T9603] kmem_cache_alloc_trace+0x153/0x7d0 [ 112.072403][ T9603] vc_allocate+0x1e2/0x6e0 [ 112.072413][ T9603] con_install+0x4f/0x400 [ 112.072422][ T9603] tty_init_dev+0xf5/0x460 [ 112.072432][ T9603] tty_open+0x47f/0xb30 [ 112.072443][ T9603] chrdev_open+0x219/0x5c0 [ 112.072454][ T9603] do_dentry_open+0x4a2/0x1250 [ 112.072465][ T9603] path_openat+0x122a/0x32b0 [ 112.072475][ T9603] do_filp_open+0x192/0x260 [ 112.072486][ T9603] do_sys_openat2+0x54c/0x740 [ 112.072496][ T9603] do_sys_open+0xc3/0x140 [ 112.072508][ T9603] do_syscall_64+0xf6/0x7d0 [ 112.072518][ T9603] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 112.072521][ T9603] [ 112.072526][ T9603] Freed by task 9602: [ 112.072536][ T9603] save_stack+0x1b/0x80 [ 112.072548][ T9603] __kasan_slab_free+0xf7/0x140 [ 112.072557][ T9603] kfree+0x109/0x2b0 [ 112.072569][ T9603] vt_disallocate_all+0x293/0x3b0 [ 112.072579][ T9603] vt_ioctl+0xb79/0x2470 [ 112.072589][ T9603] tty_ioctl+0xedd/0x1440 [ 112.072600][ T9603] ksys_ioctl+0x11a/0x180 [ 112.072611][ T9603] __x64_sys_ioctl+0x6f/0xb0 [ 112.072623][ T9603] do_syscall_64+0xf6/0x7d0 [ 112.072634][ T9603] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 112.072638][ T9603] [ 112.072648][ T9603] The buggy address belongs to the object at ffff8880956c8000 [ 112.072648][ T9603] which belongs to the cache kmalloc-2k of size 2048 [ 112.072657][ T9603] The buggy address is located 264 bytes inside of [ 112.072657][ T9603] 2048-byte region [ffff8880956c8000, ffff8880956c8800) [ 112.072661][ T9603] The buggy address belongs to the page: [ 112.072670][ T9603] page:ffffea000255b200 refcount:1 mapcount:0 mapping:ffff8880aa000e00 index:0x0 [ 112.072678][ T9603] flags: 0xfffe0000000200(slab) [ 112.072692][ T9603] raw: 00fffe0000000200 ffffea00025e7608 ffffea0002595248 ffff8880aa000e00 [ 112.072703][ T9603] raw: 0000000000000000 ffff8880956c8000 0000000100000001 0000000000000000 [ 112.072708][ T9603] page dumped because: kasan: bad access detected [ 112.072710][ T9603] [ 112.072714][ T9603] Memory state around the buggy address: [ 112.072728][ T9603] ffff8880956c8000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 112.072737][ T9603] ffff8880956c8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 112.072745][ T9603] >ffff8880956c8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 112.072748][ T9603] ^ [ 112.072756][ T9603] ffff8880956c8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 112.072764][ T9603] ffff8880956c8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 112.072768][ T9603] ================================================================== [ 112.072772][ T9603] Disabling lock debugging due to kernel taint [ 112.073233][ T9603] Kernel panic - not syncing: panic_on_warn set ... [ 112.073246][ T9603] CPU: 1 PID: 9603 Comm: syz-executor219 Tainted: G B 5.6.0-rc6-syzkaller #0 [ 112.073252][ T9603] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 112.073255][ T9603] Call Trace: [ 112.073270][ T9603] dump_stack+0x188/0x20d [ 112.073286][ T9603] panic+0x2e3/0x75c [ 112.073298][ T9603] ? add_taint.cold+0x16/0x16 [ 112.073314][ T9603] ? preempt_schedule_common+0x5e/0xc0 [ 112.073326][ T9603] ? con_shutdown+0x7f/0x90 [ 112.073338][ T9603] ? ___preempt_schedule+0x16/0x18 [ 112.073352][ T9603] ? trace_hardirqs_on+0x55/0x220 [ 112.073366][ T9603] ? con_shutdown+0x7f/0x90 [ 112.073379][ T9603] end_report+0x43/0x49 [ 112.073389][ T9603] ? con_shutdown+0x7f/0x90 [ 112.073400][ T9603] __kasan_report.cold+0xd/0x32 [ 112.073413][ T9603] ? con_shutdown+0x7f/0x90 [ 112.073426][ T9603] kasan_report+0xe/0x20 [ 112.073437][ T9603] con_shutdown+0x7f/0x90 [ 112.073447][ T9603] ? update_region+0x140/0x140 [ 112.073457][ T9603] release_tty+0xca/0x450 [ 112.073470][ T9603] tty_release_struct+0x37/0x50 [ 112.073481][ T9603] tty_release+0xbc7/0xe90 [ 112.073498][ T9603] ? do_tty_hangup+0x30/0x30 [ 112.073508][ T9603] __fput+0x2da/0x850 [ 112.073527][ T9603] task_work_run+0x13f/0x1b0 [ 112.073544][ T9603] do_exit+0xb34/0x2dd0 [ 112.073565][ T9603] ? mm_update_next_owner+0x7a0/0x7a0 [ 112.073577][ T9603] ? up_read+0x1ab/0x750 [ 112.073588][ T9603] ? mark_held_locks+0x9f/0xe0 [ 112.073601][ T9603] ? down_read_non_owner+0x470/0x470 [ 112.073617][ T9603] ? handle_mm_fault+0x491/0xa10 [ 112.073631][ T9603] do_group_exit+0x125/0x340 [ 112.073644][ T9603] __x64_sys_exit_group+0x3a/0x50 [ 112.073656][ T9603] do_syscall_64+0xf6/0x7d0 [ 112.073671][ T9603] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 112.073679][ T9603] RIP: 0033:0x43ff38 [ 112.073690][ T9603] Code: 00 00 be 3c 00 00 00 eb 19 66 0f 1f 84 00 00 00 00 00 48 89 d7 89 f0 0f 05 48 3d 00 f0 ff ff 77 21 f4 48 89 d7 44 89 c0 0f 05 <48> 3d 00 f0 ff ff 76 e0 f7 d8 64 41 89 01 eb d8 0f 1f 84 00 00 00 [ 112.073696][ T9603] RSP: 002b:00007ffce62579e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 112.073707][ T9603] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 112.073713][ T9603] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 112.073719][ T9603] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 112.073732][ T9603] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 112.073738][ T9603] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 112.074913][ T9603] Kernel Offset: disabled [ 112.826390][ T9603] Rebooting in 86400 seconds..