[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 69.179853][ T27] audit: type=1800 audit(1584345275.736:25): pid=9371 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 69.213382][ T27] audit: type=1800 audit(1584345275.736:26): pid=9371 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 69.253415][ T27] audit: type=1800 audit(1584345275.736:27): pid=9371 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 '10.128.10.14' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program syzkaller login: [ 89.271196][ T9529] ================================================================== [ 89.271257][ T9529] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 89.271267][ T9529] Write of size 8 at addr ffff88808f461108 by task syz-executor191/9529 [ 89.271269][ T9529] [ 89.271282][ T9529] CPU: 1 PID: 9529 Comm: syz-executor191 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 89.271289][ T9529] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 89.271294][ T9529] Call Trace: [ 89.271311][ T9529] dump_stack+0x188/0x20d [ 89.271325][ T9529] ? con_shutdown+0x7f/0x90 [ 89.271346][ T9529] ? con_shutdown+0x7f/0x90 [ 89.271363][ T9529] print_address_description.constprop.0.cold+0xd3/0x315 [ 89.271375][ T9529] ? con_shutdown+0x7f/0x90 [ 89.271390][ T9529] ? con_shutdown+0x7f/0x90 [ 89.271401][ T9529] __kasan_report.cold+0x1a/0x32 [ 89.271417][ T9529] ? con_shutdown+0x7f/0x90 [ 89.271433][ T9529] kasan_report+0xe/0x20 [ 89.271445][ T9529] con_shutdown+0x7f/0x90 [ 89.271458][ T9529] ? update_region+0x140/0x140 [ 89.271471][ T9529] release_tty+0xca/0x450 [ 89.271488][ T9529] tty_release_struct+0x37/0x50 [ 89.271503][ T9529] tty_release+0xbc7/0xe90 [ 89.271529][ T9529] ? do_tty_hangup+0x30/0x30 [ 89.271542][ T9529] __fput+0x2da/0x850 [ 89.271571][ T9529] task_work_run+0x13f/0x1b0 [ 89.271592][ T9529] do_exit+0xb53/0x2e10 [ 89.271621][ T9529] ? mm_update_next_owner+0x7a0/0x7a0 [ 89.271634][ T9529] ? up_read+0x1a8/0x750 [ 89.271653][ T9529] ? down_read_nested+0x430/0x430 [ 89.271671][ T9529] ? handle_mm_fault+0x29e/0x660 [ 89.271690][ T9529] do_group_exit+0x125/0x340 [ 89.271708][ T9529] __x64_sys_exit_group+0x3a/0x50 [ 89.271721][ T9529] do_syscall_64+0xf6/0x790 [ 89.271740][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.271751][ T9529] RIP: 0033:0x43ff38 [ 89.271763][ T9529] 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 [ 89.271769][ T9529] RSP: 002b:00007ffff8ec9788 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 89.271781][ T9529] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 89.271788][ T9529] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 89.271795][ T9529] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 89.271802][ T9529] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 89.271809][ T9529] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 89.271839][ T9529] [ 89.271845][ T9529] Allocated by task 9529: [ 89.271857][ T9529] save_stack+0x1b/0x40 [ 89.271869][ T9529] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 89.271880][ T9529] kmem_cache_alloc_trace+0x153/0x7d0 [ 89.271889][ T9529] vc_allocate+0x1e2/0x6e0 [ 89.271898][ T9529] con_install+0x4f/0x400 [ 89.271908][ T9529] tty_init_dev+0xf5/0x460 [ 89.271916][ T9529] tty_open+0x47f/0xb30 [ 89.271927][ T9529] chrdev_open+0x219/0x5c0 [ 89.271939][ T9529] do_dentry_open+0x49e/0x1250 [ 89.271951][ T9529] path_openat+0x122a/0x3230 [ 89.271963][ T9529] do_filp_open+0x192/0x260 [ 89.271973][ T9529] do_sys_openat2+0x54c/0x740 [ 89.271984][ T9529] do_sys_open+0xc3/0x140 [ 89.271995][ T9529] do_syscall_64+0xf6/0x790 [ 89.272006][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.272010][ T9529] [ 89.272021][ T9529] Freed by task 9535: [ 89.272033][ T9529] save_stack+0x1b/0x40 [ 89.272044][ T9529] __kasan_slab_free+0xf7/0x140 [ 89.272054][ T9529] kfree+0x109/0x2b0 [ 89.272065][ T9529] vt_disallocate_all+0x283/0x370 [ 89.272075][ T9529] vt_ioctl+0x79e/0x2450 [ 89.272086][ T9529] tty_ioctl+0xedd/0x1440 [ 89.272095][ T9529] ksys_ioctl+0x11a/0x180 [ 89.272105][ T9529] __x64_sys_ioctl+0x6f/0xb0 [ 89.272116][ T9529] do_syscall_64+0xf6/0x790 [ 89.272128][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.272131][ T9529] [ 89.272140][ T9529] The buggy address belongs to the object at ffff88808f461000 [ 89.272140][ T9529] which belongs to the cache kmalloc-2k of size 2048 [ 89.272151][ T9529] The buggy address is located 264 bytes inside of [ 89.272151][ T9529] 2048-byte region [ffff88808f461000, ffff88808f461800) [ 89.272155][ T9529] The buggy address belongs to the page: [ 89.272168][ T9529] page:ffffea00023d1840 refcount:1 mapcount:0 mapping:00000000e0b265bf index:0x0 [ 89.272177][ T9529] flags: 0xfffe0000000200(slab) [ 89.272194][ T9529] raw: 00fffe0000000200 ffffea0002487b48 ffffea00024f7dc8 ffff8880aa000e00 [ 89.272208][ T9529] raw: 0000000000000000 ffff88808f461000 0000000100000001 0000000000000000 [ 89.272213][ T9529] page dumped because: kasan: bad access detected [ 89.272217][ T9529] [ 89.272220][ T9529] Memory state around the buggy address: [ 89.272231][ T9529] ffff88808f461000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.272240][ T9529] ffff88808f461080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.272249][ T9529] >ffff88808f461100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.272253][ T9529] ^ [ 89.272262][ T9529] ffff88808f461180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.272271][ T9529] ffff88808f461200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.272275][ T9529] ================================================================== [ 89.272279][ T9529] Disabling lock debugging due to kernel taint [ 89.272332][ T9529] Kernel panic - not syncing: panic_on_warn set ... [ 89.272346][ T9529] CPU: 1 PID: 9529 Comm: syz-executor191 Tainted: G B 5.6.0-rc3-next-20200228-syzkaller #0 [ 89.272352][ T9529] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 89.272355][ T9529] Call Trace: [ 89.272368][ T9529] dump_stack+0x188/0x20d [ 89.272383][ T9529] panic+0x2e3/0x75c [ 89.272396][ T9529] ? add_taint.cold+0x16/0x16 [ 89.272406][ T9529] ? retint_kernel+0x2b/0x2b [ 89.272423][ T9529] ? trace_hardirqs_on+0x55/0x220 [ 89.272438][ T9529] ? con_shutdown+0x7f/0x90 [ 89.272448][ T9529] end_report+0x43/0x49 [ 89.272460][ T9529] ? con_shutdown+0x7f/0x90 [ 89.272469][ T9529] __kasan_report.cold+0xd/0x32 [ 89.272483][ T9529] ? con_shutdown+0x7f/0x90 [ 89.272497][ T9529] kasan_report+0xe/0x20 [ 89.272509][ T9529] con_shutdown+0x7f/0x90 [ 89.272520][ T9529] ? update_region+0x140/0x140 [ 89.272531][ T9529] release_tty+0xca/0x450 [ 89.272544][ T9529] tty_release_struct+0x37/0x50 [ 89.272557][ T9529] tty_release+0xbc7/0xe90 [ 89.272575][ T9529] ? do_tty_hangup+0x30/0x30 [ 89.272585][ T9529] __fput+0x2da/0x850 [ 89.272603][ T9529] task_work_run+0x13f/0x1b0 [ 89.272615][ T9529] do_exit+0xb53/0x2e10 [ 89.272631][ T9529] ? mm_update_next_owner+0x7a0/0x7a0 [ 89.272642][ T9529] ? up_read+0x1a8/0x750 [ 89.272654][ T9529] ? down_read_nested+0x430/0x430 [ 89.272668][ T9529] ? handle_mm_fault+0x29e/0x660 [ 89.272681][ T9529] do_group_exit+0x125/0x340 [ 89.272694][ T9529] __x64_sys_exit_group+0x3a/0x50 [ 89.272705][ T9529] do_syscall_64+0xf6/0x790 [ 89.272719][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.272726][ T9529] RIP: 0033:0x43ff38 [ 89.272738][ T9529] 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 [ 89.272744][ T9529] RSP: 002b:00007ffff8ec9788 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 89.272754][ T9529] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 89.272760][ T9529] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 89.272767][ T9529] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 89.272773][ T9529] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 89.272779][ T9529] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 89.274057][ T9529] Kernel Offset: disabled [ 90.040435][ T9529] Rebooting in 86400 seconds..