[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 62.200176][ T26] audit: type=1800 audit(1575974420.884:25): pid=9002 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 62.246165][ T26] audit: type=1800 audit(1575974420.884:26): pid=9002 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 62.288871][ T26] audit: type=1800 audit(1575974420.884:27): pid=9002 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 '10.128.1.12' (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 syzkaller login: [ 73.309201][ T9156] ================================================================== [ 73.317505][ T9156] BUG: KASAN: use-after-free in try_to_grab_pending+0x115/0x910 [ 73.325148][ T9156] Write of size 8 at addr ffff888095796008 by task syz-executor786/9156 [ 73.333623][ T9156] [ 73.335969][ T9156] CPU: 1 PID: 9156 Comm: syz-executor786 Not tainted 5.5.0-rc1-syzkaller #0 [ 73.344644][ T9156] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 73.354712][ T9156] Call Trace: [ 73.358020][ T9156] dump_stack+0x197/0x210 [ 73.362373][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.367681][ T9156] print_address_description.constprop.0.cold+0xd4/0x30b [ 73.374729][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.380034][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.385339][ T9156] __kasan_report.cold+0x1b/0x41 [ 73.390316][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.395632][ T9156] kasan_report+0x12/0x20 [ 73.399988][ T9156] check_memory_region+0x134/0x1a0 [ 73.405128][ T9156] __kasan_check_write+0x14/0x20 [ 73.410084][ T9156] try_to_grab_pending+0x115/0x910 [ 73.415239][ T9156] ? __kasan_check_read+0x11/0x20 [ 73.420294][ T9156] __cancel_work_timer+0xc4/0x540 [ 73.425348][ T9156] ? mod_delayed_work_on+0x200/0x200 [ 73.430660][ T9156] ? get_work_pool+0x1b0/0x1b0 [ 73.435454][ T9156] cancel_work_sync+0x18/0x20 [ 73.440155][ T9156] tty_buffer_cancel_work+0x16/0x20 [ 73.445367][ T9156] release_tty+0x261/0x470 [ 73.449787][ T9156] tty_release_struct+0x3c/0x50 [ 73.454639][ T9156] tty_release+0xbcb/0xe90 [ 73.459053][ T9156] __fput+0x2ff/0x890 [ 73.463042][ T9156] ? do_tty_hangup+0x30/0x30 [ 73.467620][ T9156] ____fput+0x16/0x20 [ 73.471602][ T9156] task_work_run+0x145/0x1c0 [ 73.476182][ T9156] do_exit+0x8e7/0x2ef0 [ 73.480351][ T9156] ? mm_update_next_owner+0x7c0/0x7c0 [ 73.485840][ T9156] ? down_read_non_owner+0x490/0x490 [ 73.491112][ T9156] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 73.497359][ T9156] ? handle_mm_fault+0x4ab/0xa50 [ 73.502301][ T9156] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 73.507809][ T9156] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 73.513276][ T9156] do_group_exit+0x135/0x360 [ 73.517857][ T9156] __x64_sys_exit_group+0x44/0x50 [ 73.522864][ T9156] do_syscall_64+0xfa/0x790 [ 73.527356][ T9156] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 73.533234][ T9156] RIP: 0033:0x43ff38 [ 73.537114][ T9156] 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 [ 73.556718][ T9156] RSP: 002b:00007fff9571f1f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 73.565242][ T9156] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 73.573212][ T9156] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 73.581176][ T9156] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 73.589224][ T9156] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 73.597813][ T9156] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 73.605801][ T9156] [ 73.608114][ T9156] Allocated by task 9156: [ 73.612441][ T9156] save_stack+0x23/0x90 [ 73.616588][ T9156] __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 73.622215][ T9156] kasan_kmalloc+0x9/0x10 [ 73.626532][ T9156] kmem_cache_alloc_trace+0x158/0x790 [ 73.631885][ T9156] vc_allocate+0x1fc/0x760 [ 73.636284][ T9156] con_install+0x52/0x410 [ 73.640593][ T9156] tty_init_dev+0xf9/0x470 [ 73.645004][ T9156] tty_open+0x4a5/0xbb0 [ 73.649142][ T9156] chrdev_open+0x245/0x6b0 [ 73.653543][ T9156] do_dentry_open+0x4e6/0x1380 [ 73.658287][ T9156] vfs_open+0xa0/0xd0 [ 73.662252][ T9156] path_openat+0x10df/0x4500 [ 73.666825][ T9156] do_filp_open+0x1a1/0x280 [ 73.671311][ T9156] do_sys_open+0x3fe/0x5d0 [ 73.675714][ T9156] __x64_sys_open+0x7e/0xc0 [ 73.680202][ T9156] do_syscall_64+0xfa/0x790 [ 73.684685][ T9156] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 73.690553][ T9156] [ 73.692860][ T9156] Freed by task 9165: [ 73.696827][ T9156] save_stack+0x23/0x90 [ 73.700961][ T9156] __kasan_slab_free+0x102/0x150 [ 73.705878][ T9156] kasan_slab_free+0xe/0x10 [ 73.710364][ T9156] kfree+0x10a/0x2c0 [ 73.714243][ T9156] vt_disallocate_all+0x2bd/0x3e0 [ 73.719252][ T9156] vt_ioctl+0xc38/0x26d0 [ 73.723499][ T9156] tty_ioctl+0xa37/0x14f0 [ 73.727985][ T9156] do_vfs_ioctl+0x977/0x14e0 [ 73.732661][ T9156] ksys_ioctl+0xab/0xd0 [ 73.736811][ T9156] __x64_sys_ioctl+0x73/0xb0 [ 73.741382][ T9156] do_syscall_64+0xfa/0x790 [ 73.745887][ T9156] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 73.751755][ T9156] [ 73.754066][ T9156] The buggy address belongs to the object at ffff888095796000 [ 73.754066][ T9156] which belongs to the cache kmalloc-2k of size 2048 [ 73.768102][ T9156] The buggy address is located 8 bytes inside of [ 73.768102][ T9156] 2048-byte region [ffff888095796000, ffff888095796800) [ 73.781264][ T9156] The buggy address belongs to the page: [ 73.786907][ T9156] page:ffffea000255e580 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 [ 73.796016][ T9156] raw: 00fffe0000000200 ffffea000260f988 ffffea00028c8948 ffff8880aa400e00 [ 73.804586][ T9156] raw: 0000000000000000 ffff888095796000 0000000100000001 0000000000000000 [ 73.813150][ T9156] page dumped because: kasan: bad access detected [ 73.819539][ T9156] [ 73.821852][ T9156] Memory state around the buggy address: [ 73.830881][ T9156] ffff888095795f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 73.838937][ T9156] ffff888095795f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 73.846991][ T9156] >ffff888095796000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 73.855041][ T9156] ^ [ 73.859351][ T9156] ffff888095796080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 73.867397][ T9156] ffff888095796100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 73.875439][ T9156] ================================================================== [ 73.883481][ T9156] Disabling lock debugging due to kernel taint [ 73.889621][ T9156] Kernel panic - not syncing: panic_on_warn set ... [ 73.896192][ T9156] CPU: 1 PID: 9156 Comm: syz-executor786 Tainted: G B 5.5.0-rc1-syzkaller #0 [ 73.906226][ T9156] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 73.916881][ T9156] Call Trace: [ 73.920164][ T9156] dump_stack+0x197/0x210 [ 73.924488][ T9156] panic+0x2e3/0x75c [ 73.928373][ T9156] ? add_taint.cold+0x16/0x16 [ 73.933033][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.938299][ T9156] ? trace_hardirqs_off+0x62/0x240 [ 73.943389][ T9156] ? trace_hardirqs_off+0x59/0x240 [ 73.948481][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.953752][ T9156] end_report+0x47/0x4f [ 73.957889][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.963159][ T9156] __kasan_report.cold+0xe/0x41 [ 73.967994][ T9156] ? try_to_grab_pending+0x115/0x910 [ 73.973331][ T9156] kasan_report+0x12/0x20 [ 73.977648][ T9156] check_memory_region+0x134/0x1a0 [ 73.982881][ T9156] __kasan_check_write+0x14/0x20 [ 73.987812][ T9156] try_to_grab_pending+0x115/0x910 [ 73.992909][ T9156] ? __kasan_check_read+0x11/0x20 [ 73.997932][ T9156] __cancel_work_timer+0xc4/0x540 [ 74.003062][ T9156] ? mod_delayed_work_on+0x200/0x200 [ 74.008338][ T9156] ? get_work_pool+0x1b0/0x1b0 [ 74.013103][ T9156] cancel_work_sync+0x18/0x20 [ 74.017776][ T9156] tty_buffer_cancel_work+0x16/0x20 [ 74.022969][ T9156] release_tty+0x261/0x470 [ 74.027388][ T9156] tty_release_struct+0x3c/0x50 [ 74.032231][ T9156] tty_release+0xbcb/0xe90 [ 74.036656][ T9156] __fput+0x2ff/0x890 [ 74.040633][ T9156] ? do_tty_hangup+0x30/0x30 [ 74.045209][ T9156] ____fput+0x16/0x20 [ 74.049189][ T9156] task_work_run+0x145/0x1c0 [ 74.053782][ T9156] do_exit+0x8e7/0x2ef0 [ 74.057935][ T9156] ? mm_update_next_owner+0x7c0/0x7c0 [ 74.063305][ T9156] ? down_read_non_owner+0x490/0x490 [ 74.068577][ T9156] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 74.074823][ T9156] ? handle_mm_fault+0x4ab/0xa50 [ 74.079782][ T9156] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 74.085240][ T9156] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 74.090812][ T9156] do_group_exit+0x135/0x360 [ 74.095481][ T9156] __x64_sys_exit_group+0x44/0x50 [ 74.100506][ T9156] do_syscall_64+0xfa/0x790 [ 74.105008][ T9156] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.110878][ T9156] RIP: 0033:0x43ff38 [ 74.114755][ T9156] 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 [ 74.134341][ T9156] RSP: 002b:00007fff9571f1f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 74.142735][ T9156] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 74.150702][ T9156] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 74.158656][ T9156] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 74.166615][ T9156] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 74.174602][ T9156] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 74.183808][ T9156] Kernel Offset: disabled [ 74.188141][ T9156] Rebooting in 86400 seconds..