[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 74.138224][ T27] audit: type=1800 audit(1584178596.291:25): pid=9286 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 74.158173][ T27] audit: type=1800 audit(1584178596.291:26): pid=9286 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 74.209626][ T27] audit: type=1800 audit(1584178596.291:27): pid=9286 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 '10.128.0.254' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 87.648416][ T9449] ================================================================== [ 87.648472][ T9449] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 87.648483][ T9449] Write of size 8 at addr ffff8880a6b0d108 by task syz-executor414/9449 [ 87.648486][ T9449] [ 87.648500][ T9449] CPU: 0 PID: 9449 Comm: syz-executor414 Not tainted 5.6.0-rc5-syzkaller #0 [ 87.648507][ T9449] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 87.648512][ T9449] Call Trace: [ 87.648529][ T9449] dump_stack+0x188/0x20d [ 87.648542][ T9449] ? con_shutdown+0x7f/0x90 [ 87.648556][ T9449] ? con_shutdown+0x7f/0x90 [ 87.648574][ T9449] print_address_description.constprop.0.cold+0xd3/0x315 [ 87.648584][ T9449] ? con_shutdown+0x7f/0x90 [ 87.648597][ T9449] ? con_shutdown+0x7f/0x90 [ 87.648609][ T9449] __kasan_report.cold+0x1a/0x32 [ 87.648624][ T9449] ? con_shutdown+0x7f/0x90 [ 87.648639][ T9449] kasan_report+0xe/0x20 [ 87.648651][ T9449] con_shutdown+0x7f/0x90 [ 87.648662][ T9449] ? update_region+0x140/0x140 [ 87.648674][ T9449] release_tty+0xca/0x450 [ 87.648689][ T9449] tty_release_struct+0x37/0x50 [ 87.648702][ T9449] tty_release+0xbc7/0xe90 [ 87.648730][ T9449] ? do_tty_hangup+0x30/0x30 [ 87.648741][ T9449] __fput+0x2da/0x850 [ 87.648770][ T9449] task_work_run+0x13f/0x1b0 [ 87.648795][ T9449] do_exit+0xb34/0x2dd0 [ 87.648825][ T9449] ? mm_update_next_owner+0x7a0/0x7a0 [ 87.648839][ T9449] ? up_read+0x1ab/0x750 [ 87.648853][ T9449] ? mark_held_locks+0x9f/0xe0 [ 87.648868][ T9449] ? down_read_non_owner+0x470/0x470 [ 87.648895][ T9449] ? handle_mm_fault+0x491/0xa10 [ 87.648914][ T9449] do_group_exit+0x125/0x340 [ 87.648931][ T9449] __x64_sys_exit_group+0x3a/0x50 [ 87.648946][ T9449] do_syscall_64+0xf6/0x7d0 [ 87.648966][ T9449] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.648976][ T9449] RIP: 0033:0x43ff38 [ 87.648989][ T9449] 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 [ 87.648995][ T9449] RSP: 002b:00007ffcd6309d08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 87.649007][ T9449] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 87.649014][ T9449] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 87.649021][ T9449] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 87.649029][ T9449] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 87.649036][ T9449] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 87.649064][ T9449] [ 87.649071][ T9449] Allocated by task 9449: [ 87.649088][ T9449] save_stack+0x1b/0x80 [ 87.649099][ T9449] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 87.649110][ T9449] kmem_cache_alloc_trace+0x153/0x7d0 [ 87.649119][ T9449] vc_allocate+0x1e2/0x6e0 [ 87.649129][ T9449] con_install+0x4f/0x400 [ 87.649138][ T9449] tty_init_dev+0xf5/0x460 [ 87.649146][ T9449] tty_open+0x47f/0xb30 [ 87.649156][ T9449] chrdev_open+0x219/0x5c0 [ 87.649166][ T9449] do_dentry_open+0x4a2/0x1250 [ 87.649176][ T9449] path_openat+0x122a/0x32b0 [ 87.649185][ T9449] do_filp_open+0x192/0x260 [ 87.649194][ T9449] do_sys_openat2+0x54c/0x740 [ 87.649202][ T9449] do_sys_open+0xc3/0x140 [ 87.649212][ T9449] do_syscall_64+0xf6/0x7d0 [ 87.649223][ T9449] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.649227][ T9449] [ 87.649232][ T9449] Freed by task 9450: [ 87.649241][ T9449] save_stack+0x1b/0x80 [ 87.649251][ T9449] __kasan_slab_free+0xf7/0x140 [ 87.649261][ T9449] kfree+0x109/0x2b0 [ 87.649272][ T9449] vt_disallocate_all+0x293/0x3b0 [ 87.649281][ T9449] vt_ioctl+0xb79/0x2470 [ 87.649289][ T9449] tty_ioctl+0xedd/0x1440 [ 87.649299][ T9449] ksys_ioctl+0x11a/0x180 [ 87.649308][ T9449] __x64_sys_ioctl+0x6f/0xb0 [ 87.649317][ T9449] do_syscall_64+0xf6/0x7d0 [ 87.649327][ T9449] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.649330][ T9449] [ 87.649338][ T9449] The buggy address belongs to the object at ffff8880a6b0d000 [ 87.649338][ T9449] which belongs to the cache kmalloc-2k of size 2048 [ 87.649347][ T9449] The buggy address is located 264 bytes inside of [ 87.649347][ T9449] 2048-byte region [ffff8880a6b0d000, ffff8880a6b0d800) [ 87.649351][ T9449] The buggy address belongs to the page: [ 87.649361][ T9449] page:ffffea00029ac340 refcount:1 mapcount:0 mapping:ffff8880aa000e00 index:0x0 [ 87.649370][ T9449] flags: 0xfffe0000000200(slab) [ 87.649386][ T9449] raw: 00fffe0000000200 ffffea00024d1248 ffffea0002a4c788 ffff8880aa000e00 [ 87.649398][ T9449] raw: 0000000000000000 ffff8880a6b0d000 0000000100000001 0000000000000000 [ 87.649403][ T9449] page dumped because: kasan: bad access detected [ 87.649405][ T9449] [ 87.649409][ T9449] Memory state around the buggy address: [ 87.649418][ T9449] ffff8880a6b0d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.649428][ T9449] ffff8880a6b0d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.649437][ T9449] >ffff8880a6b0d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.649440][ T9449] ^ [ 87.649449][ T9449] ffff8880a6b0d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.649457][ T9449] ffff8880a6b0d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.649462][ T9449] ================================================================== [ 87.649465][ T9449] Disabling lock debugging due to kernel taint [ 87.649660][ T9449] Kernel panic - not syncing: panic_on_warn set ... [ 87.649674][ T9449] CPU: 0 PID: 9449 Comm: syz-executor414 Tainted: G B 5.6.0-rc5-syzkaller #0 [ 87.649683][ T9449] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 87.649691][ T9449] Call Trace: [ 87.649705][ T9449] dump_stack+0x188/0x20d [ 87.649720][ T9449] panic+0x2e3/0x75c [ 87.649733][ T9449] ? add_taint.cold+0x16/0x16 [ 87.649745][ T9449] ? retint_kernel+0x2b/0x2b [ 87.649769][ T9449] ? trace_hardirqs_on+0x55/0x220 [ 87.649784][ T9449] ? con_shutdown+0x7f/0x90 [ 87.649797][ T9449] end_report+0x43/0x49 [ 87.649806][ T9449] ? con_shutdown+0x7f/0x90 [ 87.649819][ T9449] __kasan_report.cold+0xd/0x32 [ 87.649832][ T9449] ? con_shutdown+0x7f/0x90 [ 87.649846][ T9449] kasan_report+0xe/0x20 [ 87.649858][ T9449] con_shutdown+0x7f/0x90 [ 87.649870][ T9449] ? update_region+0x140/0x140 [ 87.649881][ T9449] release_tty+0xca/0x450 [ 87.649894][ T9449] tty_release_struct+0x37/0x50 [ 87.649907][ T9449] tty_release+0xbc7/0xe90 [ 87.649926][ T9449] ? do_tty_hangup+0x30/0x30 [ 87.649938][ T9449] __fput+0x2da/0x850 [ 87.649960][ T9449] task_work_run+0x13f/0x1b0 [ 87.649975][ T9449] do_exit+0xb34/0x2dd0 [ 87.650003][ T9449] ? mm_update_next_owner+0x7a0/0x7a0 [ 87.650017][ T9449] ? up_read+0x1ab/0x750 [ 87.650030][ T9449] ? mark_held_locks+0x9f/0xe0 [ 87.650044][ T9449] ? down_read_non_owner+0x470/0x470 [ 87.650059][ T9449] ? handle_mm_fault+0x491/0xa10 [ 87.650077][ T9449] do_group_exit+0x125/0x340 [ 87.650091][ T9449] __x64_sys_exit_group+0x3a/0x50 [ 87.650105][ T9449] do_syscall_64+0xf6/0x7d0 [ 87.650119][ T9449] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.650130][ T9449] RIP: 0033:0x43ff38 [ 87.650143][ T9449] 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 [ 87.650153][ T9449] RSP: 002b:00007ffcd6309d08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 87.650171][ T9449] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 87.650180][ T9449] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 87.650190][ T9449] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 87.650199][ T9449] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 87.650209][ T9449] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 87.651693][ T9449] Kernel Offset: disabled [ 88.416135][ T9449] Rebooting in 86400 seconds..