[ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.26' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 57.118468][ T7125] ================================================================== [ 57.118527][ T7125] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 57.118537][ T7125] Write of size 8 at addr ffff8880a64f6108 by task syz-executor074/7125 [ 57.118540][ T7125] [ 57.118552][ T7125] CPU: 1 PID: 7125 Comm: syz-executor074 Not tainted 5.6.0-rc7-syzkaller #0 [ 57.118558][ T7125] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 57.118563][ T7125] Call Trace: [ 57.118578][ T7125] dump_stack+0x188/0x20d [ 57.118590][ T7125] ? con_shutdown+0x7f/0x90 [ 57.118604][ T7125] ? con_shutdown+0x7f/0x90 [ 57.118623][ T7125] print_address_description.constprop.0.cold+0xd3/0x315 [ 57.118633][ T7125] ? con_shutdown+0x7f/0x90 [ 57.118645][ T7125] ? con_shutdown+0x7f/0x90 [ 57.118656][ T7125] __kasan_report.cold+0x1a/0x32 [ 57.118673][ T7125] ? con_shutdown+0x7f/0x90 [ 57.118691][ T7125] kasan_report+0xe/0x20 [ 57.118703][ T7125] con_shutdown+0x7f/0x90 [ 57.118715][ T7125] ? update_region+0x140/0x140 [ 57.118726][ T7125] release_tty+0xca/0x450 [ 57.118742][ T7125] tty_release_struct+0x37/0x50 [ 57.118756][ T7125] tty_release+0xbc7/0xe90 [ 57.118783][ T7125] ? do_tty_hangup+0x30/0x30 [ 57.118795][ T7125] __fput+0x2da/0x850 [ 57.118824][ T7125] task_work_run+0x13f/0x1b0 [ 57.118849][ T7125] do_exit+0xb34/0x2dd0 [ 57.118880][ T7125] ? mm_update_next_owner+0x7a0/0x7a0 [ 57.118901][ T7125] ? up_read+0x1ab/0x750 [ 57.118914][ T7125] ? mark_held_locks+0x9f/0xe0 [ 57.118930][ T7125] ? down_read_non_owner+0x470/0x470 [ 57.118951][ T7125] ? handle_mm_fault+0x491/0xa10 [ 57.118980][ T7125] do_group_exit+0x125/0x340 [ 57.118999][ T7125] __x64_sys_exit_group+0x3a/0x50 [ 57.119016][ T7125] do_syscall_64+0xf6/0x7d0 [ 57.119037][ T7125] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 57.119047][ T7125] RIP: 0033:0x43ff38 [ 57.119058][ T7125] Code: Bad RIP value. [ 57.119065][ T7125] RSP: 002b:00007ffc22f8fbd8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 57.119077][ T7125] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 57.119084][ T7125] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 57.119091][ T7125] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 57.119098][ T7125] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 57.119104][ T7125] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 57.119133][ T7125] [ 57.119139][ T7125] Allocated by task 7125: [ 57.119158][ T7125] save_stack+0x1b/0x80 [ 57.119170][ T7125] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 57.119181][ T7125] kmem_cache_alloc_trace+0x153/0x7d0 [ 57.119192][ T7125] vc_allocate+0x1e2/0x6e0 [ 57.119202][ T7125] con_install+0x4f/0x400 [ 57.119211][ T7125] tty_init_dev+0xf5/0x460 [ 57.119221][ T7125] tty_open+0x47f/0xb30 [ 57.119231][ T7125] chrdev_open+0x219/0x5c0 [ 57.119243][ T7125] do_dentry_open+0x4a2/0x1250 [ 57.119254][ T7125] path_openat+0x122a/0x32b0 [ 57.119264][ T7125] do_filp_open+0x192/0x260 [ 57.119275][ T7125] do_sys_openat2+0x54c/0x740 [ 57.119285][ T7125] do_sys_open+0xc3/0x140 [ 57.119295][ T7125] do_syscall_64+0xf6/0x7d0 [ 57.119306][ T7125] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 57.119309][ T7125] [ 57.119315][ T7125] Freed by task 7128: [ 57.119325][ T7125] save_stack+0x1b/0x80 [ 57.119336][ T7125] __kasan_slab_free+0xf7/0x140 [ 57.119346][ T7125] kfree+0x109/0x2b0 [ 57.119358][ T7125] vt_disallocate_all+0x293/0x3b0 [ 57.119375][ T7125] vt_ioctl+0xb79/0x2470 [ 57.119384][ T7125] tty_ioctl+0xedd/0x1440 [ 57.119395][ T7125] ksys_ioctl+0x11a/0x180 [ 57.119405][ T7125] __x64_sys_ioctl+0x6f/0xb0 [ 57.119415][ T7125] do_syscall_64+0xf6/0x7d0 [ 57.119426][ T7125] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 57.119429][ T7125] [ 57.119437][ T7125] The buggy address belongs to the object at ffff8880a64f6000 [ 57.119437][ T7125] which belongs to the cache kmalloc-2k of size 2048 [ 57.119447][ T7125] The buggy address is located 264 bytes inside of [ 57.119447][ T7125] 2048-byte region [ffff8880a64f6000, ffff8880a64f6800) [ 57.119452][ T7125] The buggy address belongs to the page: [ 57.119463][ T7125] page:ffffea0002993d80 refcount:1 mapcount:0 mapping:ffff8880aa000e00 index:0x0 [ 57.119472][ T7125] flags: 0xfffe0000000200(slab) [ 57.119486][ T7125] raw: 00fffe0000000200 ffffea0002998788 ffffea0002993d48 ffff8880aa000e00 [ 57.119498][ T7125] raw: 0000000000000000 ffff8880a64f6000 0000000100000001 0000000000000000 [ 57.119508][ T7125] page dumped because: kasan: bad access detected [ 57.119511][ T7125] [ 57.119514][ T7125] Memory state around the buggy address: [ 57.119523][ T7125] ffff8880a64f6000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 57.119531][ T7125] ffff8880a64f6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 57.119539][ T7125] >ffff8880a64f6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 57.119543][ T7125] ^ [ 57.119550][ T7125] ffff8880a64f6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 57.119558][ T7125] ffff8880a64f6200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 57.119562][ T7125] ================================================================== [ 57.119565][ T7125] Disabling lock debugging due to kernel taint [ 57.119589][ T7125] Kernel panic - not syncing: panic_on_warn set ... [ 57.119600][ T7125] CPU: 1 PID: 7125 Comm: syz-executor074 Tainted: G B 5.6.0-rc7-syzkaller #0 [ 57.119605][ T7125] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 57.119608][ T7125] Call Trace: [ 57.119619][ T7125] dump_stack+0x188/0x20d [ 57.119631][ T7125] panic+0x2e3/0x75c [ 57.119641][ T7125] ? add_taint.cold+0x16/0x16 [ 57.119649][ T7125] ? retint_kernel+0x2b/0x2b [ 57.119667][ T7125] ? trace_hardirqs_on+0x55/0x220 [ 57.119677][ T7125] ? con_shutdown+0x7f/0x90 [ 57.119688][ T7125] end_report+0x43/0x49 [ 57.119696][ T7125] ? con_shutdown+0x7f/0x90 [ 57.119705][ T7125] __kasan_report.cold+0xd/0x32 [ 57.119716][ T7125] ? con_shutdown+0x7f/0x90 [ 57.119727][ T7125] kasan_report+0xe/0x20 [ 57.119735][ T7125] con_shutdown+0x7f/0x90 [ 57.119744][ T7125] ? update_region+0x140/0x140 [ 57.119751][ T7125] release_tty+0xca/0x450 [ 57.119762][ T7125] tty_release_struct+0x37/0x50 [ 57.119771][ T7125] tty_release+0xbc7/0xe90 [ 57.119785][ T7125] ? do_tty_hangup+0x30/0x30 [ 57.119792][ T7125] __fput+0x2da/0x850 [ 57.119807][ T7125] task_work_run+0x13f/0x1b0 [ 57.119821][ T7125] do_exit+0xb34/0x2dd0 [ 57.119838][ T7125] ? mm_update_next_owner+0x7a0/0x7a0 [ 57.119848][ T7125] ? up_read+0x1ab/0x750 [ 57.119857][ T7125] ? mark_held_locks+0x9f/0xe0 [ 57.119868][ T7125] ? down_read_non_owner+0x470/0x470 [ 57.119881][ T7125] ? handle_mm_fault+0x491/0xa10 [ 57.119900][ T7125] do_group_exit+0x125/0x340 [ 57.119911][ T7125] __x64_sys_exit_group+0x3a/0x50 [ 57.119921][ T7125] do_syscall_64+0xf6/0x7d0 [ 57.119932][ T7125] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 57.119939][ T7125] RIP: 0033:0x43ff38 [ 57.119950][ T7125] Code: Bad RIP value. [ 57.119955][ T7125] RSP: 002b:00007ffc22f8fbd8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 57.119964][ T7125] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 57.119969][ T7125] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 57.119975][ T7125] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 57.119980][ T7125] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 57.119986][ T7125] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 57.121327][ T7125] Kernel Offset: disabled