[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 67.976245][ T27] audit: type=1800 audit(1584620789.678:25): pid=9297 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 68.023255][ T27] audit: type=1800 audit(1584620789.688:26): pid=9297 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 68.073310][ T27] audit: type=1800 audit(1584620789.688:27): pid=9297 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 '10.128.1.47' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 75.998237][ T9457] ================================================================== [ 75.998295][ T9457] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 75.998306][ T9457] Write of size 8 at addr ffff88809ed5c108 by task syz-executor523/9457 [ 75.998310][ T9457] [ 75.998324][ T9457] CPU: 0 PID: 9457 Comm: syz-executor523 Not tainted 5.6.0-rc6-syzkaller #0 [ 75.998331][ T9457] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 75.998335][ T9457] Call Trace: [ 75.998354][ T9457] dump_stack+0x188/0x20d [ 75.998367][ T9457] ? con_shutdown+0x7f/0x90 [ 75.998379][ T9457] ? con_shutdown+0x7f/0x90 [ 75.998399][ T9457] print_address_description.constprop.0.cold+0xd3/0x315 [ 75.998410][ T9457] ? con_shutdown+0x7f/0x90 [ 75.998423][ T9457] ? con_shutdown+0x7f/0x90 [ 75.998434][ T9457] __kasan_report.cold+0x1a/0x32 [ 75.998452][ T9457] ? con_shutdown+0x7f/0x90 [ 75.998470][ T9457] kasan_report+0xe/0x20 [ 75.998482][ T9457] con_shutdown+0x7f/0x90 [ 75.998493][ T9457] ? update_region+0x140/0x140 [ 75.998504][ T9457] release_tty+0xca/0x450 [ 75.998520][ T9457] tty_release_struct+0x37/0x50 [ 75.998533][ T9457] tty_release+0xbc7/0xe90 [ 75.998560][ T9457] ? do_tty_hangup+0x30/0x30 [ 75.998571][ T9457] __fput+0x2da/0x850 [ 75.998599][ T9457] task_work_run+0x13f/0x1b0 [ 75.998624][ T9457] do_exit+0xb34/0x2dd0 [ 75.998657][ T9457] ? mm_update_next_owner+0x7a0/0x7a0 [ 75.998672][ T9457] ? up_read+0x1ab/0x750 [ 75.998703][ T9457] ? mark_held_locks+0x9f/0xe0 [ 75.998719][ T9457] ? down_read_non_owner+0x470/0x470 [ 75.998741][ T9457] ? handle_mm_fault+0x491/0xa10 [ 75.998762][ T9457] do_group_exit+0x125/0x340 [ 75.998781][ T9457] __x64_sys_exit_group+0x3a/0x50 [ 75.998796][ T9457] do_syscall_64+0xf6/0x7d0 [ 75.998817][ T9457] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 75.998827][ T9457] RIP: 0033:0x43ff38 [ 75.998840][ T9457] 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 [ 75.998847][ T9457] RSP: 002b:00007ffd486980e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 75.998859][ T9457] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 75.998866][ T9457] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 75.998879][ T9457] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 75.998887][ T9457] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 75.998894][ T9457] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 75.998925][ T9457] [ 75.998931][ T9457] Allocated by task 9457: [ 75.998943][ T9457] save_stack+0x1b/0x80 [ 75.998955][ T9457] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 75.998966][ T9457] kmem_cache_alloc_trace+0x153/0x7d0 [ 75.998977][ T9457] vc_allocate+0x1e2/0x6e0 [ 75.998987][ T9457] con_install+0x4f/0x400 [ 75.998998][ T9457] tty_init_dev+0xf5/0x460 [ 75.999007][ T9457] tty_open+0x47f/0xb30 [ 75.999019][ T9457] chrdev_open+0x219/0x5c0 [ 75.999029][ T9457] do_dentry_open+0x4a2/0x1250 [ 75.999040][ T9457] path_openat+0x122a/0x32b0 [ 75.999050][ T9457] do_filp_open+0x192/0x260 [ 75.999059][ T9457] do_sys_openat2+0x54c/0x740 [ 75.999069][ T9457] do_sys_open+0xc3/0x140 [ 75.999079][ T9457] do_syscall_64+0xf6/0x7d0 [ 75.999090][ T9457] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 75.999094][ T9457] [ 75.999099][ T9457] Freed by task 9459: [ 75.999110][ T9457] save_stack+0x1b/0x80 [ 75.999122][ T9457] __kasan_slab_free+0xf7/0x140 [ 75.999132][ T9457] kfree+0x109/0x2b0 [ 75.999143][ T9457] vt_disallocate_all+0x293/0x3b0 [ 75.999154][ T9457] vt_ioctl+0xb79/0x2470 [ 75.999164][ T9457] tty_ioctl+0xedd/0x1440 [ 75.999176][ T9457] ksys_ioctl+0x11a/0x180 [ 75.999187][ T9457] __x64_sys_ioctl+0x6f/0xb0 [ 75.999199][ T9457] do_syscall_64+0xf6/0x7d0 [ 75.999210][ T9457] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 75.999214][ T9457] [ 75.999222][ T9457] The buggy address belongs to the object at ffff88809ed5c000 [ 75.999222][ T9457] which belongs to the cache kmalloc-2k of size 2048 [ 75.999233][ T9457] The buggy address is located 264 bytes inside of [ 75.999233][ T9457] 2048-byte region [ffff88809ed5c000, ffff88809ed5c800) [ 75.999238][ T9457] The buggy address belongs to the page: [ 75.999250][ T9457] page:ffffea00027b5700 refcount:1 mapcount:0 mapping:ffff8880aa000e00 index:0x0 [ 75.999259][ T9457] flags: 0xfffe0000000200(slab) [ 75.999276][ T9457] raw: 00fffe0000000200 ffffea00027b55c8 ffffea00027b5748 ffff8880aa000e00 [ 75.999290][ T9457] raw: 0000000000000000 ffff88809ed5c000 0000000100000001 0000000000000000 [ 75.999295][ T9457] page dumped because: kasan: bad access detected [ 75.999298][ T9457] [ 75.999302][ T9457] Memory state around the buggy address: [ 75.999311][ T9457] ffff88809ed5c000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 75.999321][ T9457] ffff88809ed5c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 75.999331][ T9457] >ffff88809ed5c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 75.999336][ T9457] ^ [ 75.999346][ T9457] ffff88809ed5c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 75.999355][ T9457] ffff88809ed5c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 75.999360][ T9457] ================================================================== [ 75.999364][ T9457] Disabling lock debugging due to kernel taint [ 75.999482][ T9457] Kernel panic - not syncing: panic_on_warn set ... [ 75.999496][ T9457] CPU: 0 PID: 9457 Comm: syz-executor523 Tainted: G B 5.6.0-rc6-syzkaller #0 [ 75.999502][ T9457] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 75.999506][ T9457] Call Trace: [ 75.999519][ T9457] dump_stack+0x188/0x20d [ 75.999534][ T9457] panic+0x2e3/0x75c [ 75.999546][ T9457] ? add_taint.cold+0x16/0x16 [ 75.999562][ T9457] ? preempt_schedule_common+0x5e/0xc0 [ 75.999574][ T9457] ? con_shutdown+0x7f/0x90 [ 75.999586][ T9457] ? ___preempt_schedule+0x16/0x18 [ 75.999600][ T9457] ? trace_hardirqs_on+0x55/0x220 [ 75.999613][ T9457] ? con_shutdown+0x7f/0x90 [ 75.999625][ T9457] end_report+0x43/0x49 [ 75.999636][ T9457] ? con_shutdown+0x7f/0x90 [ 75.999647][ T9457] __kasan_report.cold+0xd/0x32 [ 75.999660][ T9457] ? con_shutdown+0x7f/0x90 [ 75.999674][ T9457] kasan_report+0xe/0x20 [ 75.999685][ T9457] con_shutdown+0x7f/0x90 [ 75.999696][ T9457] ? update_region+0x140/0x140 [ 75.999705][ T9457] release_tty+0xca/0x450 [ 75.999718][ T9457] tty_release_struct+0x37/0x50 [ 75.999729][ T9457] tty_release+0xbc7/0xe90 [ 75.999747][ T9457] ? do_tty_hangup+0x30/0x30 [ 75.999757][ T9457] __fput+0x2da/0x850 [ 75.999775][ T9457] task_work_run+0x13f/0x1b0 [ 75.999792][ T9457] do_exit+0xb34/0x2dd0 [ 75.999814][ T9457] ? mm_update_next_owner+0x7a0/0x7a0 [ 75.999826][ T9457] ? up_read+0x1ab/0x750 [ 75.999837][ T9457] ? mark_held_locks+0x9f/0xe0 [ 75.999850][ T9457] ? down_read_non_owner+0x470/0x470 [ 75.999866][ T9457] ? handle_mm_fault+0x491/0xa10 [ 75.999885][ T9457] do_group_exit+0x125/0x340 [ 75.999899][ T9457] __x64_sys_exit_group+0x3a/0x50 [ 75.999911][ T9457] do_syscall_64+0xf6/0x7d0 [ 75.999925][ T9457] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 75.999933][ T9457] RIP: 0033:0x43ff38 [ 75.999944][ T9457] 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 [ 75.999950][ T9457] RSP: 002b:00007ffd486980e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 75.999960][ T9457] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 75.999967][ T9457] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 75.999973][ T9457] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 75.999979][ T9457] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 75.999985][ T9457] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 76.001418][ T9457] Kernel Offset: disabled