[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 71.206471][ T27] audit: type=1800 audit(1578608473.535:25): pid=9364 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 71.226230][ T27] audit: type=1800 audit(1578608473.535:26): pid=9364 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 71.269368][ T27] audit: type=1800 audit(1578608473.535:27): pid=9364 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 '10.128.0.167' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 82.374438][ T9529] ================================================================== [ 82.383160][ T9529] BUG: KASAN: use-after-free in try_to_grab_pending+0x115/0x910 [ 82.383179][ T9529] Write of size 8 at addr ffff8880a20b7008 by task syz-executor680/9529 [ 82.383184][ T9529] [ 82.383201][ T9529] CPU: 0 PID: 9529 Comm: syz-executor680 Not tainted 5.5.0-rc5-syzkaller #0 [ 82.383210][ T9529] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 82.383216][ T9529] Call Trace: [ 82.383232][ T9529] dump_stack+0x197/0x210 [ 82.383248][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.383270][ T9529] print_address_description.constprop.0.cold+0xd4/0x30b [ 82.383285][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.383300][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.383315][ T9529] __kasan_report.cold+0x1b/0x41 [ 82.383333][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.383350][ T9529] kasan_report+0x12/0x20 [ 82.383367][ T9529] check_memory_region+0x134/0x1a0 [ 82.383383][ T9529] __kasan_check_write+0x14/0x20 [ 82.383398][ T9529] try_to_grab_pending+0x115/0x910 [ 82.383411][ T9529] ? __kasan_check_read+0x11/0x20 [ 82.383430][ T9529] __cancel_work_timer+0xc4/0x540 [ 82.383448][ T9529] ? mod_delayed_work_on+0x200/0x200 [ 82.383468][ T9529] ? get_work_pool+0x1b0/0x1b0 [ 82.383495][ T9529] cancel_work_sync+0x18/0x20 [ 82.383511][ T9529] tty_buffer_cancel_work+0x16/0x20 [ 82.383527][ T9529] release_tty+0x261/0x470 [ 82.383554][ T9529] tty_release_struct+0x3c/0x50 [ 82.383571][ T9529] tty_release+0xbcb/0xe90 [ 82.383595][ T9529] __fput+0x2ff/0x890 [ 82.383612][ T9529] ? do_tty_hangup+0x30/0x30 [ 82.383628][ T9529] ____fput+0x16/0x20 [ 82.383643][ T9529] task_work_run+0x145/0x1c0 [ 82.383664][ T9529] do_exit+0xba9/0x2f50 [ 82.383691][ T9529] ? mm_update_next_owner+0x7c0/0x7c0 [ 82.383709][ T9529] ? down_read_non_owner+0x490/0x490 [ 82.383728][ T9529] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 82.383743][ T9529] ? handle_mm_fault+0x4ab/0xa50 [ 82.383762][ T9529] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 82.383777][ T9529] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 82.383797][ T9529] do_group_exit+0x135/0x360 [ 82.383818][ T9529] __x64_sys_exit_group+0x44/0x50 [ 82.383835][ T9529] do_syscall_64+0xfa/0x790 [ 82.383854][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 82.383865][ T9529] RIP: 0033:0x43ff38 [ 82.383876][ T9529] Code: Bad RIP value. [ 82.383884][ T9529] RSP: 002b:00007ffe16093138 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 82.383898][ T9529] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 82.383906][ T9529] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 82.383915][ T9529] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 82.383924][ T9529] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 82.383932][ T9529] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 82.383952][ T9529] [ 82.383959][ T9529] Allocated by task 9520: [ 82.383971][ T9529] save_stack+0x23/0x90 [ 82.383984][ T9529] __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 82.383996][ T9529] kasan_kmalloc+0x9/0x10 [ 82.384008][ T9529] kmem_cache_alloc_trace+0x158/0x790 [ 82.384022][ T9529] vc_allocate+0x1fc/0x760 [ 82.384036][ T9529] con_install+0x52/0x410 [ 82.384049][ T9529] tty_init_dev+0xf9/0x470 [ 82.384062][ T9529] tty_open+0x4a5/0xbb0 [ 82.384072][ T9529] chrdev_open+0x245/0x6b0 [ 82.384086][ T9529] do_dentry_open+0x4e6/0x1380 [ 82.384097][ T9529] vfs_open+0xa0/0xd0 [ 82.384110][ T9529] path_openat+0x10df/0x4500 [ 82.384123][ T9529] do_filp_open+0x1a1/0x280 [ 82.384135][ T9529] do_sys_open+0x3fe/0x5d0 [ 82.384146][ T9529] __x64_sys_open+0x7e/0xc0 [ 82.384159][ T9529] do_syscall_64+0xfa/0x790 [ 82.384170][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 82.384173][ T9529] [ 82.384179][ T9529] Freed by task 9526: [ 82.384190][ T9529] save_stack+0x23/0x90 [ 82.384202][ T9529] __kasan_slab_free+0x102/0x150 [ 82.384215][ T9529] kasan_slab_free+0xe/0x10 [ 82.384226][ T9529] kfree+0x10a/0x2c0 [ 82.384237][ T9529] vt_disallocate_all+0x2bd/0x3e0 [ 82.384248][ T9529] vt_ioctl+0xc38/0x26d0 [ 82.384261][ T9529] tty_ioctl+0xa37/0x14f0 [ 82.384274][ T9529] do_vfs_ioctl+0x977/0x14e0 [ 82.384285][ T9529] ksys_ioctl+0xab/0xd0 [ 82.384298][ T9529] __x64_sys_ioctl+0x73/0xb0 [ 82.384313][ T9529] do_syscall_64+0xfa/0x790 [ 82.384326][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 82.384330][ T9529] [ 82.384341][ T9529] The buggy address belongs to the object at ffff8880a20b7000 [ 82.384341][ T9529] which belongs to the cache kmalloc-2k of size 2048 [ 82.384354][ T9529] The buggy address is located 8 bytes inside of [ 82.384354][ T9529] 2048-byte region [ffff8880a20b7000, ffff8880a20b7800) [ 82.384359][ T9529] The buggy address belongs to the page: [ 82.384371][ T9529] page:ffffea0002882dc0 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 [ 82.384390][ T9529] raw: 00fffe0000000200 ffffea0002880748 ffffea0002880788 ffff8880aa400e00 [ 82.384407][ T9529] raw: 0000000000000000 ffff8880a20b7000 0000000100000001 0000000000000000 [ 82.384414][ T9529] page dumped because: kasan: bad access detected [ 82.384417][ T9529] [ 82.384422][ T9529] Memory state around the buggy address: [ 82.384435][ T9529] ffff8880a20b6f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 82.384446][ T9529] ffff8880a20b6f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 82.384458][ T9529] >ffff8880a20b7000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 82.384463][ T9529] ^ [ 82.384475][ T9529] ffff8880a20b7080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 82.384487][ T9529] ffff8880a20b7100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 82.384492][ T9529] ================================================================== [ 82.384497][ T9529] Disabling lock debugging due to kernel taint [ 82.384505][ T9529] Kernel panic - not syncing: panic_on_warn set ... [ 82.384521][ T9529] CPU: 0 PID: 9529 Comm: syz-executor680 Tainted: G B 5.5.0-rc5-syzkaller #0 [ 82.384528][ T9529] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 82.384531][ T9529] Call Trace: [ 82.384554][ T9529] dump_stack+0x197/0x210 [ 82.384570][ T9529] panic+0x2e3/0x75c [ 82.384584][ T9529] ? add_taint.cold+0x16/0x16 [ 82.384601][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.384617][ T9529] ? trace_hardirqs_off+0x62/0x240 [ 82.384631][ T9529] ? trace_hardirqs_off+0x59/0x240 [ 82.384647][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.384660][ T9529] end_report+0x47/0x4f [ 82.384674][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.384687][ T9529] __kasan_report.cold+0xe/0x41 [ 82.384702][ T9529] ? try_to_grab_pending+0x115/0x910 [ 82.384716][ T9529] kasan_report+0x12/0x20 [ 82.384731][ T9529] check_memory_region+0x134/0x1a0 [ 82.384745][ T9529] __kasan_check_write+0x14/0x20 [ 82.384759][ T9529] try_to_grab_pending+0x115/0x910 [ 82.384771][ T9529] ? __kasan_check_read+0x11/0x20 [ 82.384787][ T9529] __cancel_work_timer+0xc4/0x540 [ 82.384802][ T9529] ? mod_delayed_work_on+0x200/0x200 [ 82.384816][ T9529] ? get_work_pool+0x1b0/0x1b0 [ 82.384834][ T9529] cancel_work_sync+0x18/0x20 [ 82.384847][ T9529] tty_buffer_cancel_work+0x16/0x20 [ 82.384860][ T9529] release_tty+0x261/0x470 [ 82.384875][ T9529] tty_release_struct+0x3c/0x50 [ 82.384890][ T9529] tty_release+0xbcb/0xe90 [ 82.384907][ T9529] __fput+0x2ff/0x890 [ 82.384923][ T9529] ? do_tty_hangup+0x30/0x30 [ 82.384936][ T9529] ____fput+0x16/0x20 [ 82.384949][ T9529] task_work_run+0x145/0x1c0 [ 82.384967][ T9529] do_exit+0xba9/0x2f50 [ 82.384987][ T9529] ? mm_update_next_owner+0x7c0/0x7c0 [ 82.385003][ T9529] ? down_read_non_owner+0x490/0x490 [ 82.385020][ T9529] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 82.385034][ T9529] ? handle_mm_fault+0x4ab/0xa50 [ 82.385050][ T9529] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 82.385065][ T9529] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 82.385082][ T9529] do_group_exit+0x135/0x360 [ 82.385099][ T9529] __x64_sys_exit_group+0x44/0x50 [ 82.385114][ T9529] do_syscall_64+0xfa/0x790 [ 82.385130][ T9529] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 82.385139][ T9529] RIP: 0033:0x43ff38 [ 82.385149][ T9529] Code: Bad RIP value. [ 82.385156][ T9529] RSP: 002b:00007ffe16093138 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 82.385169][ T9529] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 82.385177][ T9529] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 82.385184][ T9529] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 82.385190][ T9529] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 82.385198][ T9529] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 82.386588][ T9529] Kernel Offset: disabled [ 83.216124][ T9529] Rebooting in 86400 seconds..