[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 75.016991][ T27] audit: type=1800 audit(1585094201.810:25): pid=9484 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 75.055475][ T27] audit: type=1800 audit(1585094201.810:26): pid=9484 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 75.095304][ T27] audit: type=1800 audit(1585094201.820:27): pid=9484 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 '10.128.0.141' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 86.784896][ T9670] ================================================================== [ 86.784954][ T9670] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 86.784970][ T9670] Write of size 8 at addr ffff8880a612f108 by task syz-executor699/9670 [ 86.784974][ T9670] [ 86.784988][ T9670] CPU: 1 PID: 9670 Comm: syz-executor699 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 86.784995][ T9670] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 86.784999][ T9670] Call Trace: [ 86.785017][ T9670] dump_stack+0x188/0x20d [ 86.785031][ T9670] ? con_shutdown+0x7f/0x90 [ 86.785046][ T9670] ? con_shutdown+0x7f/0x90 [ 86.785062][ T9670] print_address_description.constprop.0.cold+0xd3/0x315 [ 86.785075][ T9670] ? con_shutdown+0x7f/0x90 [ 86.785089][ T9670] ? con_shutdown+0x7f/0x90 [ 86.785099][ T9670] __kasan_report.cold+0x1a/0x32 [ 86.785118][ T9670] ? con_shutdown+0x7f/0x90 [ 86.785137][ T9670] kasan_report+0xe/0x20 [ 86.785151][ T9670] con_shutdown+0x7f/0x90 [ 86.785168][ T9670] ? update_region+0x140/0x140 [ 86.785180][ T9670] release_tty+0xca/0x450 [ 86.785196][ T9670] tty_release_struct+0x37/0x50 [ 86.785208][ T9670] tty_release+0xbc7/0xe90 [ 86.785234][ T9670] ? do_tty_hangup+0x30/0x30 [ 86.785245][ T9670] __fput+0x2da/0x850 [ 86.785273][ T9670] task_work_run+0x13f/0x1b0 [ 86.785295][ T9670] do_exit+0xb53/0x2e10 [ 86.785324][ T9670] ? mm_update_next_owner+0x7a0/0x7a0 [ 86.785338][ T9670] ? up_read+0x1a8/0x750 [ 86.785357][ T9670] ? down_read_nested+0x430/0x430 [ 86.785377][ T9670] ? handle_mm_fault+0x29e/0x660 [ 86.785397][ T9670] do_group_exit+0x125/0x340 [ 86.785415][ T9670] __x64_sys_exit_group+0x3a/0x50 [ 86.785430][ T9670] do_syscall_64+0xf6/0x790 [ 86.785449][ T9670] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 86.785460][ T9670] RIP: 0033:0x43ff38 [ 86.785471][ T9670] Code: Bad RIP value. [ 86.785482][ T9670] RSP: 002b:00007fffc9eb96a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 86.785493][ T9670] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 86.785500][ T9670] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 86.785508][ T9670] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 86.785515][ T9670] R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000001 [ 86.785522][ T9670] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 86.785551][ T9670] [ 86.785558][ T9670] Allocated by task 9670: [ 86.785570][ T9670] save_stack+0x1b/0x40 [ 86.785583][ T9670] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 86.785594][ T9670] kmem_cache_alloc_trace+0x153/0x7d0 [ 86.785603][ T9670] vc_allocate+0x1e2/0x6e0 [ 86.785612][ T9670] con_install+0x4f/0x400 [ 86.785623][ T9670] tty_init_dev+0xf5/0x460 [ 86.785632][ T9670] tty_open+0x47f/0xb30 [ 86.785643][ T9670] chrdev_open+0x219/0x5c0 [ 86.785659][ T9670] do_dentry_open+0x49e/0x1250 [ 86.785671][ T9670] path_openat+0x122a/0x3230 [ 86.785681][ T9670] do_filp_open+0x192/0x260 [ 86.785691][ T9670] do_sys_openat2+0x54c/0x740 [ 86.785702][ T9670] do_sys_open+0xc3/0x140 [ 86.785713][ T9670] do_syscall_64+0xf6/0x790 [ 86.785724][ T9670] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 86.785728][ T9670] [ 86.785733][ T9670] Freed by task 9672: [ 86.785744][ T9670] save_stack+0x1b/0x40 [ 86.785762][ T9670] __kasan_slab_free+0xf7/0x140 [ 86.785772][ T9670] kfree+0x109/0x2b0 [ 86.785782][ T9670] vt_disallocate_all+0x283/0x370 [ 86.785791][ T9670] vt_ioctl+0x79e/0x2450 [ 86.785803][ T9670] tty_ioctl+0xedd/0x1440 [ 86.785812][ T9670] ksys_ioctl+0x11a/0x180 [ 86.785821][ T9670] __x64_sys_ioctl+0x6f/0xb0 [ 86.785832][ T9670] do_syscall_64+0xf6/0x790 [ 86.785842][ T9670] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 86.785846][ T9670] [ 86.785859][ T9670] The buggy address belongs to the object at ffff8880a612f000 [ 86.785859][ T9670] which belongs to the cache kmalloc-2k of size 2048 [ 86.785870][ T9670] The buggy address is located 264 bytes inside of [ 86.785870][ T9670] 2048-byte region [ffff8880a612f000, ffff8880a612f800) [ 86.785874][ T9670] The buggy address belongs to the page: [ 86.785886][ T9670] page:ffffea0002984bc0 refcount:1 mapcount:0 mapping:000000003319ee2b index:0x0 [ 86.785894][ T9670] flags: 0xfffe0000000200(slab) [ 86.785911][ T9670] raw: 00fffe0000000200 ffffea0002884c08 ffffea00027b9988 ffff8880aa000e00 [ 86.785925][ T9670] raw: 0000000000000000 ffff8880a612f000 0000000100000001 0000000000000000 [ 86.785930][ T9670] page dumped because: kasan: bad access detected [ 86.785933][ T9670] [ 86.785936][ T9670] Memory state around the buggy address: [ 86.785944][ T9670] ffff8880a612f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 86.785952][ T9670] ffff8880a612f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 86.785959][ T9670] >ffff8880a612f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 86.785963][ T9670] ^ [ 86.785973][ T9670] ffff8880a612f180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 86.785982][ T9670] ffff8880a612f200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 86.785987][ T9670] ================================================================== [ 86.785991][ T9670] Disabling lock debugging due to kernel taint [ 86.786440][ T9670] Kernel panic - not syncing: panic_on_warn set ... [ 86.786454][ T9670] CPU: 1 PID: 9670 Comm: syz-executor699 Tainted: G B 5.6.0-rc3-next-20200228-syzkaller #0 [ 86.786461][ T9670] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 86.786464][ T9670] Call Trace: [ 86.786477][ T9670] dump_stack+0x188/0x20d [ 86.786492][ T9670] panic+0x2e3/0x75c [ 86.786504][ T9670] ? add_taint.cold+0x16/0x16 [ 86.786514][ T9670] ? retint_kernel+0x2b/0x2b [ 86.786532][ T9670] ? trace_hardirqs_on+0x55/0x220 [ 86.786546][ T9670] ? con_shutdown+0x7f/0x90 [ 86.786555][ T9670] end_report+0x43/0x49 [ 86.786565][ T9670] ? con_shutdown+0x7f/0x90 [ 86.786574][ T9670] __kasan_report.cold+0xd/0x32 [ 86.786588][ T9670] ? con_shutdown+0x7f/0x90 [ 86.786600][ T9670] kasan_report+0xe/0x20 [ 86.786612][ T9670] con_shutdown+0x7f/0x90 [ 86.786623][ T9670] ? update_region+0x140/0x140 [ 86.786632][ T9670] release_tty+0xca/0x450 [ 86.786644][ T9670] tty_release_struct+0x37/0x50 [ 86.786667][ T9670] tty_release+0xbc7/0xe90 [ 86.786685][ T9670] ? do_tty_hangup+0x30/0x30 [ 86.786695][ T9670] __fput+0x2da/0x850 [ 86.786713][ T9670] task_work_run+0x13f/0x1b0 [ 86.786726][ T9670] do_exit+0xb53/0x2e10 [ 86.786744][ T9670] ? mm_update_next_owner+0x7a0/0x7a0 [ 86.786763][ T9670] ? up_read+0x1a8/0x750 [ 86.786783][ T9670] ? down_read_nested+0x430/0x430 [ 86.786796][ T9670] ? handle_mm_fault+0x29e/0x660 [ 86.786810][ T9670] do_group_exit+0x125/0x340 [ 86.786823][ T9670] __x64_sys_exit_group+0x3a/0x50 [ 86.786834][ T9670] do_syscall_64+0xf6/0x790 [ 86.786847][ T9670] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 86.786855][ T9670] RIP: 0033:0x43ff38 [ 86.786864][ T9670] Code: Bad RIP value. [ 86.786869][ T9670] RSP: 002b:00007fffc9eb96a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 86.786880][ T9670] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 86.786886][ T9670] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 86.786893][ T9670] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 86.786899][ T9670] R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000001 [ 86.786905][ T9670] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 86.788725][ T9670] Kernel Offset: disabled