[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 63.004713][ T27] audit: type=1800 audit(1585509044.627:25): pid=9264 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 63.040950][ T27] audit: type=1800 audit(1585509044.627:26): pid=9264 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 63.081148][ T27] audit: type=1800 audit(1585509044.637:27): pid=9264 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 '10.128.1.37' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program syzkaller login: [ 87.992413][ T9424] ================================================================== [ 87.992471][ T9424] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 87.992482][ T9424] Write of size 8 at addr ffff8880a28ba108 by task syz-executor042/9424 [ 87.992485][ T9424] [ 87.992499][ T9424] CPU: 1 PID: 9424 Comm: syz-executor042 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 87.992507][ T9424] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 87.992511][ T9424] Call Trace: [ 87.992528][ T9424] dump_stack+0x188/0x20d [ 87.992542][ T9424] ? con_shutdown+0x7f/0x90 [ 87.992556][ T9424] ? con_shutdown+0x7f/0x90 [ 87.992573][ T9424] print_address_description.constprop.0.cold+0xd3/0x315 [ 87.992585][ T9424] ? con_shutdown+0x7f/0x90 [ 87.992597][ T9424] ? con_shutdown+0x7f/0x90 [ 87.992606][ T9424] __kasan_report.cold+0x1a/0x32 [ 87.992621][ T9424] ? con_shutdown+0x7f/0x90 [ 87.992638][ T9424] kasan_report+0xe/0x20 [ 87.992651][ T9424] con_shutdown+0x7f/0x90 [ 87.992663][ T9424] ? update_region+0x140/0x140 [ 87.992676][ T9424] release_tty+0xca/0x450 [ 87.992700][ T9424] tty_release_struct+0x37/0x50 [ 87.992714][ T9424] tty_release+0xbc7/0xe90 [ 87.992740][ T9424] ? do_tty_hangup+0x30/0x30 [ 87.992751][ T9424] __fput+0x2da/0x850 [ 87.992779][ T9424] task_work_run+0x13f/0x1b0 [ 87.992800][ T9424] do_exit+0xb53/0x2e10 [ 87.992828][ T9424] ? mm_update_next_owner+0x7a0/0x7a0 [ 87.992842][ T9424] ? up_read+0x1a8/0x750 [ 87.992860][ T9424] ? down_read_nested+0x430/0x430 [ 87.992876][ T9424] ? handle_mm_fault+0x29e/0x660 [ 87.992895][ T9424] do_group_exit+0x125/0x340 [ 87.992912][ T9424] __x64_sys_exit_group+0x3a/0x50 [ 87.992928][ T9424] do_syscall_64+0xf6/0x790 [ 87.992947][ T9424] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.992957][ T9424] RIP: 0033:0x43ff38 [ 87.992970][ T9424] 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 [ 87.992977][ T9424] RSP: 002b:00007ffd2af91768 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 87.992988][ T9424] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 87.992995][ T9424] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 87.993002][ T9424] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 87.993010][ T9424] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 87.993016][ T9424] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 87.993045][ T9424] [ 87.993050][ T9424] Allocated by task 9424: [ 87.993062][ T9424] save_stack+0x1b/0x40 [ 87.993075][ T9424] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 87.993086][ T9424] kmem_cache_alloc_trace+0x153/0x7d0 [ 87.993102][ T9424] vc_allocate+0x1e2/0x6e0 [ 87.993110][ T9424] con_install+0x4f/0x400 [ 87.993121][ T9424] tty_init_dev+0xf5/0x460 [ 87.993128][ T9424] tty_open+0x47f/0xb30 [ 87.993139][ T9424] chrdev_open+0x219/0x5c0 [ 87.993151][ T9424] do_dentry_open+0x49e/0x1250 [ 87.993161][ T9424] path_openat+0x122a/0x3230 [ 87.993171][ T9424] do_filp_open+0x192/0x260 [ 87.993181][ T9424] do_sys_openat2+0x54c/0x740 [ 87.993192][ T9424] do_sys_open+0xc3/0x140 [ 87.993203][ T9424] do_syscall_64+0xf6/0x790 [ 87.993215][ T9424] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.993217][ T9424] [ 87.993222][ T9424] Freed by task 9425: [ 87.993232][ T9424] save_stack+0x1b/0x40 [ 87.993243][ T9424] __kasan_slab_free+0xf7/0x140 [ 87.993253][ T9424] kfree+0x109/0x2b0 [ 87.993263][ T9424] vt_disallocate_all+0x283/0x370 [ 87.993272][ T9424] vt_ioctl+0x79e/0x2450 [ 87.993283][ T9424] tty_ioctl+0xedd/0x1440 [ 87.993292][ T9424] ksys_ioctl+0x11a/0x180 [ 87.993302][ T9424] __x64_sys_ioctl+0x6f/0xb0 [ 87.993313][ T9424] do_syscall_64+0xf6/0x790 [ 87.993323][ T9424] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.993326][ T9424] [ 87.993334][ T9424] The buggy address belongs to the object at ffff8880a28ba000 [ 87.993334][ T9424] which belongs to the cache kmalloc-2k of size 2048 [ 87.993344][ T9424] The buggy address is located 264 bytes inside of [ 87.993344][ T9424] 2048-byte region [ffff8880a28ba000, ffff8880a28ba800) [ 87.993348][ T9424] The buggy address belongs to the page: [ 87.993360][ T9424] page:ffffea00028a2e80 refcount:1 mapcount:0 mapping:00000000b69478b5 index:0x0 [ 87.993369][ T9424] flags: 0xfffe0000000200(slab) [ 87.993386][ T9424] raw: 00fffe0000000200 ffffea000299f948 ffffea000299eb08 ffff8880aa000e00 [ 87.993399][ T9424] raw: 0000000000000000 ffff8880a28ba000 0000000100000001 0000000000000000 [ 87.993405][ T9424] page dumped because: kasan: bad access detected [ 87.993408][ T9424] [ 87.993412][ T9424] Memory state around the buggy address: [ 87.993422][ T9424] ffff8880a28ba000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.993430][ T9424] ffff8880a28ba080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.993440][ T9424] >ffff8880a28ba100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.993444][ T9424] ^ [ 87.993454][ T9424] ffff8880a28ba180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.993463][ T9424] ffff8880a28ba200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 87.993467][ T9424] ================================================================== [ 87.993471][ T9424] Disabling lock debugging due to kernel taint [ 87.993520][ T9424] Kernel panic - not syncing: panic_on_warn set ... [ 87.993533][ T9424] CPU: 1 PID: 9424 Comm: syz-executor042 Tainted: G B 5.6.0-rc3-next-20200228-syzkaller #0 [ 87.993539][ T9424] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 87.993542][ T9424] Call Trace: [ 87.993556][ T9424] dump_stack+0x188/0x20d [ 87.993570][ T9424] panic+0x2e3/0x75c [ 87.993581][ T9424] ? add_taint.cold+0x16/0x16 [ 87.993590][ T9424] ? retint_kernel+0x2b/0x2b [ 87.993604][ T9424] ? trace_hardirqs_on+0x55/0x220 [ 87.993618][ T9424] ? con_shutdown+0x7f/0x90 [ 87.993628][ T9424] end_report+0x43/0x49 [ 87.993638][ T9424] ? con_shutdown+0x7f/0x90 [ 87.993646][ T9424] __kasan_report.cold+0xd/0x32 [ 87.993659][ T9424] ? con_shutdown+0x7f/0x90 [ 87.993672][ T9424] kasan_report+0xe/0x20 [ 87.993683][ T9424] con_shutdown+0x7f/0x90 [ 87.993695][ T9424] ? update_region+0x140/0x140 [ 87.993706][ T9424] release_tty+0xca/0x450 [ 87.993720][ T9424] tty_release_struct+0x37/0x50 [ 87.993732][ T9424] tty_release+0xbc7/0xe90 [ 87.993751][ T9424] ? do_tty_hangup+0x30/0x30 [ 87.993760][ T9424] __fput+0x2da/0x850 [ 87.993776][ T9424] task_work_run+0x13f/0x1b0 [ 87.993790][ T9424] do_exit+0xb53/0x2e10 [ 87.993806][ T9424] ? mm_update_next_owner+0x7a0/0x7a0 [ 87.993817][ T9424] ? up_read+0x1a8/0x750 [ 87.993830][ T9424] ? down_read_nested+0x430/0x430 [ 87.993841][ T9424] ? handle_mm_fault+0x29e/0x660 [ 87.993854][ T9424] do_group_exit+0x125/0x340 [ 87.993867][ T9424] __x64_sys_exit_group+0x3a/0x50 [ 87.993878][ T9424] do_syscall_64+0xf6/0x790 [ 87.993892][ T9424] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.993905][ T9424] RIP: 0033:0x43ff38 [ 87.993917][ T9424] 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 [ 87.993923][ T9424] RSP: 002b:00007ffd2af91768 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 87.993934][ T9424] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 87.993940][ T9424] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 87.993947][ T9424] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 87.993952][ T9424] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 87.993958][ T9424] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 87.995407][ T9424] Kernel Offset: disabled [ 88.744691][ T9424] Rebooting in 86400 seconds..