[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 62.706385][ T27] audit: type=1800 audit(1575972733.589:25): pid=9110 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 62.727007][ T27] audit: type=1800 audit(1575972733.589:26): pid=9110 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 62.754130][ T27] audit: type=1800 audit(1575972733.589:27): pid=9110 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 '10.128.0.86' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program syzkaller login: [ 89.309105][ T9267] ================================================================== [ 89.318141][ T9267] BUG: KASAN: use-after-free in try_to_grab_pending+0x115/0x910 [ 89.326394][ T9267] Write of size 8 at addr ffff8880a79ec008 by task syz-executor094/9267 [ 89.337225][ T9267] [ 89.340187][ T9267] CPU: 1 PID: 9267 Comm: syz-executor094 Not tainted 5.5.0-rc1-syzkaller #0 [ 89.349144][ T9267] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 89.365550][ T9267] Call Trace: [ 89.369970][ T9267] dump_stack+0x197/0x210 [ 89.375749][ T9267] ? try_to_grab_pending+0x115/0x910 [ 89.382707][ T9267] print_address_description.constprop.0.cold+0xd4/0x30b [ 89.391558][ T9267] ? try_to_grab_pending+0x115/0x910 [ 89.398462][ T9267] ? try_to_grab_pending+0x115/0x910 [ 89.404976][ T9267] __kasan_report.cold+0x1b/0x41 [ 89.410953][ T9267] ? try_to_grab_pending+0x115/0x910 [ 89.417041][ T9267] kasan_report+0x12/0x20 [ 89.422006][ T9267] check_memory_region+0x134/0x1a0 [ 89.428560][ T9267] __kasan_check_write+0x14/0x20 [ 89.434114][ T9267] try_to_grab_pending+0x115/0x910 [ 89.441152][ T9267] ? __kasan_check_read+0x11/0x20 [ 89.446659][ T9267] __cancel_work_timer+0xc4/0x540 [ 89.453384][ T9267] ? mod_delayed_work_on+0x200/0x200 [ 89.459258][ T9267] ? get_work_pool+0x1b0/0x1b0 [ 89.464812][ T9267] cancel_work_sync+0x18/0x20 [ 89.469742][ T9267] tty_buffer_cancel_work+0x16/0x20 [ 89.475621][ T9267] release_tty+0x261/0x470 [ 89.480347][ T9267] tty_release_struct+0x3c/0x50 [ 89.485808][ T9267] tty_release+0xbcb/0xe90 [ 89.490828][ T9267] __fput+0x2ff/0x890 [ 89.495066][ T9267] ? do_tty_hangup+0x30/0x30 [ 89.499947][ T9267] ____fput+0x16/0x20 [ 89.504192][ T9267] task_work_run+0x145/0x1c0 [ 89.509526][ T9267] do_exit+0x8e7/0x2ef0 [ 89.514282][ T9267] ? mm_update_next_owner+0x7c0/0x7c0 [ 89.520234][ T9267] ? down_read_non_owner+0x490/0x490 [ 89.526244][ T9267] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 89.533403][ T9267] ? handle_mm_fault+0x4ab/0xa50 [ 89.540258][ T9267] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 89.546978][ T9267] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 89.555572][ T9267] do_group_exit+0x135/0x360 [ 89.561332][ T9267] __x64_sys_exit_group+0x44/0x50 [ 89.567129][ T9267] do_syscall_64+0xfa/0x790 [ 89.573058][ T9267] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.579767][ T9267] RIP: 0033:0x43ff38 [ 89.583911][ T9267] Code: Bad RIP value. [ 89.588183][ T9267] RSP: 002b:00007ffd413d1ec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 89.597881][ T9267] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 89.607803][ T9267] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 89.618998][ T9267] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 89.628907][ T9267] R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000001 [ 89.640551][ T9267] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 89.651448][ T9267] [ 89.655658][ T9267] Allocated by task 9267: [ 89.664364][ T9267] save_stack+0x23/0x90 [ 89.673646][ T9267] __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 89.683612][ T9267] kasan_kmalloc+0x9/0x10 [ 89.688943][ T9267] kmem_cache_alloc_trace+0x158/0x790 [ 89.695590][ T9267] vc_allocate+0x1fc/0x760 [ 89.701371][ T9267] con_install+0x52/0x410 [ 89.706642][ T9267] tty_init_dev+0xf9/0x470 [ 89.711737][ T9267] tty_open+0x4a5/0xbb0 [ 89.716203][ T9267] chrdev_open+0x245/0x6b0 [ 89.720975][ T9267] do_dentry_open+0x4e6/0x1380 [ 89.726450][ T9267] vfs_open+0xa0/0xd0 [ 89.731011][ T9267] path_openat+0x10df/0x4500 [ 89.737780][ T9267] do_filp_open+0x1a1/0x280 [ 89.743138][ T9267] do_sys_open+0x3fe/0x5d0 [ 89.747833][ T9267] __x64_sys_open+0x7e/0xc0 [ 89.752974][ T9267] do_syscall_64+0xfa/0x790 [ 89.758016][ T9267] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.764223][ T9267] [ 89.766889][ T9267] Freed by task 9274: [ 89.771364][ T9267] save_stack+0x23/0x90 [ 89.776028][ T9267] __kasan_slab_free+0x102/0x150 [ 89.781278][ T9267] kasan_slab_free+0xe/0x10 [ 89.786307][ T9267] kfree+0x10a/0x2c0 [ 89.790524][ T9267] vt_disallocate_all+0x2bd/0x3e0 [ 89.796493][ T9267] vt_ioctl+0xc38/0x26d0 [ 89.801311][ T9267] tty_ioctl+0xa37/0x14f0 [ 89.805746][ T9267] do_vfs_ioctl+0x977/0x14e0 [ 89.810861][ T9267] ksys_ioctl+0xab/0xd0 [ 89.815460][ T9267] __x64_sys_ioctl+0x73/0xb0 [ 89.821073][ T9267] do_syscall_64+0xfa/0x790 [ 89.825886][ T9267] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.832482][ T9267] [ 89.834826][ T9267] The buggy address belongs to the object at ffff8880a79ec000 [ 89.834826][ T9267] which belongs to the cache kmalloc-2k of size 2048 [ 89.850594][ T9267] The buggy address is located 8 bytes inside of [ 89.850594][ T9267] 2048-byte region [ffff8880a79ec000, ffff8880a79ec800) [ 89.865768][ T9267] The buggy address belongs to the page: [ 89.872129][ T9267] page:ffffea00029e7b00 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 [ 89.882262][ T9267] raw: 00fffe0000000200 ffffea00029c1088 ffffea00029e7b48 ffff8880aa400e00 [ 89.892684][ T9267] raw: 0000000000000000 ffff8880a79ec000 0000000100000001 0000000000000000 [ 89.903284][ T9267] page dumped because: kasan: bad access detected [ 89.910539][ T9267] [ 89.913241][ T9267] Memory state around the buggy address: [ 89.921757][ T9267] ffff8880a79ebf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 89.932800][ T9267] ffff8880a79ebf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 89.943274][ T9267] >ffff8880a79ec000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.954798][ T9267] ^ [ 89.960183][ T9267] ffff8880a79ec080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.969525][ T9267] ffff8880a79ec100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 89.979530][ T9267] ================================================================== [ 89.990520][ T9267] Disabling lock debugging due to kernel taint [ 89.997676][ T9267] Kernel panic - not syncing: panic_on_warn set ... [ 90.005561][ T9267] CPU: 1 PID: 9267 Comm: syz-executor094 Tainted: G B 5.5.0-rc1-syzkaller #0 [ 90.019073][ T9267] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 90.031146][ T9267] Call Trace: [ 90.035279][ T9267] dump_stack+0x197/0x210 [ 90.041285][ T9267] panic+0x2e3/0x75c [ 90.046154][ T9267] ? add_taint.cold+0x16/0x16 [ 90.052702][ T9267] ? try_to_grab_pending+0x115/0x910 [ 90.060088][ T9267] ? trace_hardirqs_off+0x62/0x240 [ 90.067552][ T9267] ? trace_hardirqs_off+0x59/0x240 [ 90.073343][ T9267] ? try_to_grab_pending+0x115/0x910 [ 90.080229][ T9267] end_report+0x47/0x4f [ 90.085985][ T9267] ? try_to_grab_pending+0x115/0x910 [ 90.093536][ T9267] __kasan_report.cold+0xe/0x41 [ 90.099769][ T9267] ? try_to_grab_pending+0x115/0x910 [ 90.105980][ T9267] kasan_report+0x12/0x20 [ 90.110781][ T9267] check_memory_region+0x134/0x1a0 [ 90.117621][ T9267] __kasan_check_write+0x14/0x20 [ 90.123043][ T9267] try_to_grab_pending+0x115/0x910 [ 90.128599][ T9267] ? __kasan_check_read+0x11/0x20 [ 90.135193][ T9267] __cancel_work_timer+0xc4/0x540 [ 90.140699][ T9267] ? mod_delayed_work_on+0x200/0x200 [ 90.147203][ T9267] ? get_work_pool+0x1b0/0x1b0 [ 90.154764][ T9267] cancel_work_sync+0x18/0x20 [ 90.161312][ T9267] tty_buffer_cancel_work+0x16/0x20 [ 90.167450][ T9267] release_tty+0x261/0x470 [ 90.172876][ T9267] tty_release_struct+0x3c/0x50 [ 90.179631][ T9267] tty_release+0xbcb/0xe90 [ 90.185371][ T9267] __fput+0x2ff/0x890 [ 90.199637][ T9267] ? do_tty_hangup+0x30/0x30 [ 90.205228][ T9267] ____fput+0x16/0x20 [ 90.210261][ T9267] task_work_run+0x145/0x1c0 [ 90.216721][ T9267] do_exit+0x8e7/0x2ef0 [ 90.222109][ T9267] ? mm_update_next_owner+0x7c0/0x7c0 [ 90.228230][ T9267] ? down_read_non_owner+0x490/0x490 [ 90.234738][ T9267] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 90.246978][ T9267] ? handle_mm_fault+0x4ab/0xa50 [ 90.252801][ T9267] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 90.258899][ T9267] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 90.265102][ T9267] do_group_exit+0x135/0x360 [ 90.270712][ T9267] __x64_sys_exit_group+0x44/0x50 [ 90.277713][ T9267] do_syscall_64+0xfa/0x790 [ 90.286002][ T9267] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 90.293642][ T9267] RIP: 0033:0x43ff38 [ 90.297537][ T9267] Code: Bad RIP value. [ 90.301899][ T9267] RSP: 002b:00007ffd413d1ec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 90.310434][ T9267] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 90.318543][ T9267] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 90.326518][ T9267] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 90.334596][ T9267] R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000001 [ 90.342853][ T9267] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 90.353211][ T9267] Kernel Offset: disabled [ 90.357807][ T9267] Rebooting in 86400 seconds..