[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 69.181023][ T27] audit: type=1800 audit(1584862693.484:25): pid=9427 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 69.218809][ T27] audit: type=1800 audit(1584862693.484:26): pid=9427 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 69.252707][ T27] audit: type=1800 audit(1584862693.494:27): pid=9427 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 '10.128.1.19' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program syzkaller login: [ 91.747429][ T9591] ================================================================== [ 91.747488][ T9591] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 91.747499][ T9591] Write of size 8 at addr ffff88809f00e108 by task syz-executor232/9591 [ 91.747502][ T9591] [ 91.747516][ T9591] CPU: 0 PID: 9591 Comm: syz-executor232 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 91.747523][ T9591] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 91.747528][ T9591] Call Trace: [ 91.747545][ T9591] dump_stack+0x188/0x20d [ 91.747558][ T9591] ? con_shutdown+0x7f/0x90 [ 91.747571][ T9591] ? con_shutdown+0x7f/0x90 [ 91.747587][ T9591] print_address_description.constprop.0.cold+0xd3/0x315 [ 91.747607][ T9591] ? con_shutdown+0x7f/0x90 [ 91.747621][ T9591] ? con_shutdown+0x7f/0x90 [ 91.747631][ T9591] __kasan_report.cold+0x1a/0x32 [ 91.747650][ T9591] ? con_shutdown+0x7f/0x90 [ 91.747668][ T9591] kasan_report+0xe/0x20 [ 91.747680][ T9591] con_shutdown+0x7f/0x90 [ 91.747693][ T9591] ? update_region+0x140/0x140 [ 91.747706][ T9591] release_tty+0xca/0x450 [ 91.747723][ T9591] tty_release_struct+0x37/0x50 [ 91.747738][ T9591] tty_release+0xbc7/0xe90 [ 91.747765][ T9591] ? do_tty_hangup+0x30/0x30 [ 91.747776][ T9591] __fput+0x2da/0x850 [ 91.747802][ T9591] task_work_run+0x13f/0x1b0 [ 91.747822][ T9591] do_exit+0xb53/0x2e10 [ 91.747851][ T9591] ? mm_update_next_owner+0x7a0/0x7a0 [ 91.747864][ T9591] ? up_read+0x1a8/0x750 [ 91.747881][ T9591] ? down_read_nested+0x430/0x430 [ 91.747898][ T9591] ? handle_mm_fault+0x29e/0x660 [ 91.747915][ T9591] do_group_exit+0x125/0x340 [ 91.747930][ T9591] __x64_sys_exit_group+0x3a/0x50 [ 91.747944][ T9591] do_syscall_64+0xf6/0x790 [ 91.747963][ T9591] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 91.747974][ T9591] RIP: 0033:0x43ff38 [ 91.747986][ T9591] 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 [ 91.747993][ T9591] RSP: 002b:00007ffc254a1a48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 91.748005][ T9591] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 91.748012][ T9591] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 91.748019][ T9591] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 91.748027][ T9591] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 91.748034][ T9591] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 91.748063][ T9591] [ 91.748070][ T9591] Allocated by task 9591: [ 91.748083][ T9591] save_stack+0x1b/0x40 [ 91.748095][ T9591] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 91.748107][ T9591] kmem_cache_alloc_trace+0x153/0x7d0 [ 91.748117][ T9591] vc_allocate+0x1e2/0x6e0 [ 91.748127][ T9591] con_install+0x4f/0x400 [ 91.748138][ T9591] tty_init_dev+0xf5/0x460 [ 91.748146][ T9591] tty_open+0x47f/0xb30 [ 91.748156][ T9591] chrdev_open+0x219/0x5c0 [ 91.748168][ T9591] do_dentry_open+0x49e/0x1250 [ 91.748179][ T9591] path_openat+0x122a/0x3230 [ 91.748191][ T9591] do_filp_open+0x192/0x260 [ 91.748202][ T9591] do_sys_openat2+0x54c/0x740 [ 91.748211][ T9591] do_sys_open+0xc3/0x140 [ 91.748221][ T9591] do_syscall_64+0xf6/0x790 [ 91.748230][ T9591] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 91.748233][ T9591] [ 91.748238][ T9591] Freed by task 9582: [ 91.748248][ T9591] save_stack+0x1b/0x40 [ 91.748258][ T9591] __kasan_slab_free+0xf7/0x140 [ 91.748266][ T9591] kfree+0x109/0x2b0 [ 91.748275][ T9591] vt_disallocate_all+0x283/0x370 [ 91.748284][ T9591] vt_ioctl+0x79e/0x2450 [ 91.748295][ T9591] tty_ioctl+0xedd/0x1440 [ 91.748311][ T9591] ksys_ioctl+0x11a/0x180 [ 91.748321][ T9591] __x64_sys_ioctl+0x6f/0xb0 [ 91.748332][ T9591] do_syscall_64+0xf6/0x790 [ 91.748344][ T9591] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 91.748347][ T9591] [ 91.748357][ T9591] The buggy address belongs to the object at ffff88809f00e000 [ 91.748357][ T9591] which belongs to the cache kmalloc-2k of size 2048 [ 91.748367][ T9591] The buggy address is located 264 bytes inside of [ 91.748367][ T9591] 2048-byte region [ffff88809f00e000, ffff88809f00e800) [ 91.748371][ T9591] The buggy address belongs to the page: [ 91.748384][ T9591] page:ffffea00027c0380 refcount:1 mapcount:0 mapping:000000007fc76bda index:0x0 [ 91.748400][ T9591] flags: 0xfffe0000000200(slab) [ 91.748416][ T9591] raw: 00fffe0000000200 ffffea00027a2888 ffffea00024926c8 ffff8880aa000e00 [ 91.748431][ T9591] raw: 0000000000000000 ffff88809f00e000 0000000100000001 0000000000000000 [ 91.748436][ T9591] page dumped because: kasan: bad access detected [ 91.748439][ T9591] [ 91.748443][ T9591] Memory state around the buggy address: [ 91.748453][ T9591] ffff88809f00e000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 91.748463][ T9591] ffff88809f00e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 91.748473][ T9591] >ffff88809f00e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 91.748477][ T9591] ^ [ 91.748487][ T9591] ffff88809f00e180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 91.748496][ T9591] ffff88809f00e200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 91.748501][ T9591] ================================================================== [ 91.748505][ T9591] Disabling lock debugging due to kernel taint [ 91.748528][ T9591] Kernel panic - not syncing: panic_on_warn set ... [ 91.748540][ T9591] CPU: 0 PID: 9591 Comm: syz-executor232 Tainted: G B 5.6.0-rc3-next-20200228-syzkaller #0 [ 91.748546][ T9591] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 91.748549][ T9591] Call Trace: [ 91.748561][ T9591] dump_stack+0x188/0x20d [ 91.748576][ T9591] panic+0x2e3/0x75c [ 91.748588][ T9591] ? add_taint.cold+0x16/0x16 [ 91.748602][ T9591] ? retint_kernel+0x2b/0x2b [ 91.748617][ T9591] ? trace_hardirqs_on+0x55/0x220 [ 91.748630][ T9591] ? con_shutdown+0x7f/0x90 [ 91.748639][ T9591] end_report+0x43/0x49 [ 91.748649][ T9591] ? con_shutdown+0x7f/0x90 [ 91.748658][ T9591] __kasan_report.cold+0xd/0x32 [ 91.748672][ T9591] ? con_shutdown+0x7f/0x90 [ 91.748685][ T9591] kasan_report+0xe/0x20 [ 91.748697][ T9591] con_shutdown+0x7f/0x90 [ 91.748708][ T9591] ? update_region+0x140/0x140 [ 91.748718][ T9591] release_tty+0xca/0x450 [ 91.748731][ T9591] tty_release_struct+0x37/0x50 [ 91.748744][ T9591] tty_release+0xbc7/0xe90 [ 91.748762][ T9591] ? do_tty_hangup+0x30/0x30 [ 91.748772][ T9591] __fput+0x2da/0x850 [ 91.748790][ T9591] task_work_run+0x13f/0x1b0 [ 91.748804][ T9591] do_exit+0xb53/0x2e10 [ 91.748821][ T9591] ? mm_update_next_owner+0x7a0/0x7a0 [ 91.748833][ T9591] ? up_read+0x1a8/0x750 [ 91.748846][ T9591] ? down_read_nested+0x430/0x430 [ 91.748859][ T9591] ? handle_mm_fault+0x29e/0x660 [ 91.748882][ T9591] do_group_exit+0x125/0x340 [ 91.748894][ T9591] __x64_sys_exit_group+0x3a/0x50 [ 91.748906][ T9591] do_syscall_64+0xf6/0x790 [ 91.748919][ T9591] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 91.748927][ T9591] RIP: 0033:0x43ff38 [ 91.748939][ T9591] 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 [ 91.748945][ T9591] RSP: 002b:00007ffc254a1a48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 91.748956][ T9591] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 91.748962][ T9591] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 91.748969][ T9591] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 91.748976][ T9591] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 91.748982][ T9591] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 91.750807][ T9591] Kernel Offset: disabled [ 92.512490][ T9591] Rebooting in 86400 seconds..