[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 65.128753][ T27] audit: type=1800 audit(1585123090.996:25): pid=9525 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 65.163616][ T27] audit: type=1800 audit(1585123090.996:26): pid=9525 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 65.216937][ T27] audit: type=1800 audit(1585123091.006:27): pid=9525 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 '10.128.0.215' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 74.804675][ T9685] ================================================================== [ 74.804732][ T9685] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 74.804743][ T9685] Write of size 8 at addr ffff8880a87ec108 by task syz-executor170/9685 [ 74.804746][ T9685] [ 74.804760][ T9685] CPU: 1 PID: 9685 Comm: syz-executor170 Not tainted 5.6.0-rc7-syzkaller #0 [ 74.804766][ T9685] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 74.804770][ T9685] Call Trace: [ 74.804787][ T9685] dump_stack+0x188/0x20d [ 74.804800][ T9685] ? con_shutdown+0x7f/0x90 [ 74.804814][ T9685] ? con_shutdown+0x7f/0x90 [ 74.804834][ T9685] print_address_description.constprop.0.cold+0xd3/0x315 [ 74.804846][ T9685] ? con_shutdown+0x7f/0x90 [ 74.804860][ T9685] ? con_shutdown+0x7f/0x90 [ 74.804872][ T9685] __kasan_report.cold+0x1a/0x32 [ 74.804890][ T9685] ? con_shutdown+0x7f/0x90 [ 74.804908][ T9685] kasan_report+0xe/0x20 [ 74.804920][ T9685] con_shutdown+0x7f/0x90 [ 74.804931][ T9685] ? update_region+0x140/0x140 [ 74.804942][ T9685] release_tty+0xca/0x450 [ 74.804958][ T9685] tty_release_struct+0x37/0x50 [ 74.804971][ T9685] tty_release+0xbc7/0xe90 [ 74.804998][ T9685] ? do_tty_hangup+0x30/0x30 [ 74.805009][ T9685] __fput+0x2da/0x850 [ 74.805037][ T9685] task_work_run+0x13f/0x1b0 [ 74.805061][ T9685] do_exit+0xb34/0x2dd0 [ 74.805093][ T9685] ? mm_update_next_owner+0x7a0/0x7a0 [ 74.805106][ T9685] ? up_read+0x1ab/0x750 [ 74.805119][ T9685] ? mark_held_locks+0x9f/0xe0 [ 74.805133][ T9685] ? down_read_non_owner+0x470/0x470 [ 74.805154][ T9685] ? handle_mm_fault+0x491/0xa10 [ 74.805174][ T9685] do_group_exit+0x125/0x340 [ 74.805191][ T9685] __x64_sys_exit_group+0x3a/0x50 [ 74.805206][ T9685] do_syscall_64+0xf6/0x7d0 [ 74.805227][ T9685] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.805237][ T9685] RIP: 0033:0x43ff38 [ 74.805248][ T9685] Code: Bad RIP value. [ 74.805254][ T9685] RSP: 002b:00007ffefbf7c538 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 74.805265][ T9685] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 74.805271][ T9685] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 74.805278][ T9685] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 74.805284][ T9685] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 74.805290][ T9685] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 74.805318][ T9685] [ 74.805324][ T9685] Allocated by task 9685: [ 74.805336][ T9685] save_stack+0x1b/0x80 [ 74.805348][ T9685] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 74.805359][ T9685] kmem_cache_alloc_trace+0x153/0x7d0 [ 74.805370][ T9685] vc_allocate+0x1e2/0x6e0 [ 74.805380][ T9685] con_install+0x4f/0x400 [ 74.805390][ T9685] tty_init_dev+0xf5/0x460 [ 74.805400][ T9685] tty_open+0x47f/0xb30 [ 74.805411][ T9685] chrdev_open+0x219/0x5c0 [ 74.805422][ T9685] do_dentry_open+0x4a2/0x1250 [ 74.805432][ T9685] path_openat+0x122a/0x32b0 [ 74.805443][ T9685] do_filp_open+0x192/0x260 [ 74.805453][ T9685] do_sys_openat2+0x54c/0x740 [ 74.805463][ T9685] do_sys_open+0xc3/0x140 [ 74.805474][ T9685] do_syscall_64+0xf6/0x7d0 [ 74.805484][ T9685] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.805487][ T9685] [ 74.805492][ T9685] Freed by task 9686: [ 74.805503][ T9685] save_stack+0x1b/0x80 [ 74.805513][ T9685] __kasan_slab_free+0xf7/0x140 [ 74.805523][ T9685] kfree+0x109/0x2b0 [ 74.805534][ T9685] vt_disallocate_all+0x293/0x3b0 [ 74.805545][ T9685] vt_ioctl+0xb79/0x2470 [ 74.805555][ T9685] tty_ioctl+0xedd/0x1440 [ 74.805565][ T9685] ksys_ioctl+0x11a/0x180 [ 74.805577][ T9685] __x64_sys_ioctl+0x6f/0xb0 [ 74.805588][ T9685] do_syscall_64+0xf6/0x7d0 [ 74.805599][ T9685] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.805603][ T9685] [ 74.805618][ T9685] The buggy address belongs to the object at ffff8880a87ec000 [ 74.805618][ T9685] which belongs to the cache kmalloc-2k of size 2048 [ 74.805629][ T9685] The buggy address is located 264 bytes inside of [ 74.805629][ T9685] 2048-byte region [ffff8880a87ec000, ffff8880a87ec800) [ 74.805633][ T9685] The buggy address belongs to the page: [ 74.805644][ T9685] page:ffffea0002a1fb00 refcount:1 mapcount:0 mapping:ffff8880aa000e00 index:0x0 [ 74.805654][ T9685] flags: 0xfffe0000000200(slab) [ 74.805671][ T9685] raw: 00fffe0000000200 ffffea00029ff388 ffffea00027cccc8 ffff8880aa000e00 [ 74.805685][ T9685] raw: 0000000000000000 ffff8880a87ec000 0000000100000001 0000000000000000 [ 74.805690][ T9685] page dumped because: kasan: bad access detected [ 74.805693][ T9685] [ 74.805697][ T9685] Memory state around the buggy address: [ 74.805708][ T9685] ffff8880a87ec000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.805717][ T9685] ffff8880a87ec080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.805727][ T9685] >ffff8880a87ec100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.805732][ T9685] ^ [ 74.805741][ T9685] ffff8880a87ec180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.805750][ T9685] ffff8880a87ec200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.805755][ T9685] ================================================================== [ 74.805759][ T9685] Disabling lock debugging due to kernel taint [ 74.805765][ T9685] Kernel panic - not syncing: panic_on_warn set ... [ 74.805778][ T9685] CPU: 1 PID: 9685 Comm: syz-executor170 Tainted: G B 5.6.0-rc7-syzkaller #0 [ 74.805784][ T9685] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 74.805787][ T9685] Call Trace: [ 74.805800][ T9685] dump_stack+0x188/0x20d [ 74.805815][ T9685] panic+0x2e3/0x75c [ 74.805827][ T9685] ? add_taint.cold+0x16/0x16 [ 74.805845][ T9685] ? print_shadow_for_address+0xb8/0x114 [ 74.805858][ T9685] ? trace_hardirqs_on+0x55/0x220 [ 74.805872][ T9685] ? con_shutdown+0x7f/0x90 [ 74.805885][ T9685] end_report+0x43/0x49 [ 74.805896][ T9685] ? con_shutdown+0x7f/0x90 [ 74.805907][ T9685] __kasan_report.cold+0xd/0x32 [ 74.805919][ T9685] ? con_shutdown+0x7f/0x90 [ 74.805933][ T9685] kasan_report+0xe/0x20 [ 74.805944][ T9685] con_shutdown+0x7f/0x90 [ 74.805956][ T9685] ? update_region+0x140/0x140 [ 74.805965][ T9685] release_tty+0xca/0x450 [ 74.805977][ T9685] tty_release_struct+0x37/0x50 [ 74.805989][ T9685] tty_release+0xbc7/0xe90 [ 74.806006][ T9685] ? do_tty_hangup+0x30/0x30 [ 74.806015][ T9685] __fput+0x2da/0x850 [ 74.806034][ T9685] task_work_run+0x13f/0x1b0 [ 74.806050][ T9685] do_exit+0xb34/0x2dd0 [ 74.806071][ T9685] ? mm_update_next_owner+0x7a0/0x7a0 [ 74.806083][ T9685] ? up_read+0x1ab/0x750 [ 74.806094][ T9685] ? mark_held_locks+0x9f/0xe0 [ 74.806107][ T9685] ? down_read_non_owner+0x470/0x470 [ 74.806122][ T9685] ? handle_mm_fault+0x491/0xa10 [ 74.806135][ T9685] do_group_exit+0x125/0x340 [ 74.806148][ T9685] __x64_sys_exit_group+0x3a/0x50 [ 74.806160][ T9685] do_syscall_64+0xf6/0x7d0 [ 74.806175][ T9685] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.806182][ T9685] RIP: 0033:0x43ff38 [ 74.806190][ T9685] Code: Bad RIP value. [ 74.806196][ T9685] RSP: 002b:00007ffefbf7c538 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 74.806206][ T9685] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 74.806213][ T9685] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 74.806219][ T9685] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 74.806226][ T9685] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 74.806232][ T9685] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 74.807849][ T9685] Kernel Offset: disabled [ 75.534614][ T9685] Rebooting in 86400 seconds..