[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 61.068317][ T27] audit: type=1800 audit(1584657959.021:25): pid=9320 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 61.106070][ T27] audit: type=1800 audit(1584657959.021:26): pid=9320 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 61.138271][ T27] audit: type=1800 audit(1584657959.021:27): pid=9320 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 '10.128.1.50' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 71.844739][ T9476] ================================================================== [ 71.844799][ T9476] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 71.844810][ T9476] Write of size 8 at addr ffff88809f3d8108 by task syz-executor052/9476 [ 71.844813][ T9476] [ 71.844826][ T9476] CPU: 1 PID: 9476 Comm: syz-executor052 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 71.844833][ T9476] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 71.844838][ T9476] Call Trace: [ 71.844854][ T9476] dump_stack+0x188/0x20d [ 71.844867][ T9476] ? con_shutdown+0x7f/0x90 [ 71.844880][ T9476] ? con_shutdown+0x7f/0x90 [ 71.844896][ T9476] print_address_description.constprop.0.cold+0xd3/0x315 [ 71.844909][ T9476] ? con_shutdown+0x7f/0x90 [ 71.844924][ T9476] ? con_shutdown+0x7f/0x90 [ 71.844935][ T9476] __kasan_report.cold+0x1a/0x32 [ 71.844951][ T9476] ? con_shutdown+0x7f/0x90 [ 71.844969][ T9476] kasan_report+0xe/0x20 [ 71.845000][ T9476] con_shutdown+0x7f/0x90 [ 71.845013][ T9476] ? update_region+0x140/0x140 [ 71.845026][ T9476] release_tty+0xca/0x450 [ 71.845044][ T9476] tty_release_struct+0x37/0x50 [ 71.845059][ T9476] tty_release+0xbc7/0xe90 [ 71.845088][ T9476] ? do_tty_hangup+0x30/0x30 [ 71.845100][ T9476] __fput+0x2da/0x850 [ 71.845129][ T9476] task_work_run+0x13f/0x1b0 [ 71.845151][ T9476] do_exit+0xb53/0x2e10 [ 71.845181][ T9476] ? mm_update_next_owner+0x7a0/0x7a0 [ 71.845194][ T9476] ? up_read+0x1a8/0x750 [ 71.845218][ T9476] ? down_read_nested+0x430/0x430 [ 71.845238][ T9476] ? handle_mm_fault+0x29e/0x660 [ 71.845256][ T9476] do_group_exit+0x125/0x340 [ 71.845274][ T9476] __x64_sys_exit_group+0x3a/0x50 [ 71.845290][ T9476] do_syscall_64+0xf6/0x790 [ 71.845310][ T9476] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.845320][ T9476] RIP: 0033:0x43ff38 [ 71.845332][ T9476] Code: Bad RIP value. [ 71.845339][ T9476] RSP: 002b:00007ffd8ecdcb78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 71.845351][ T9476] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 71.845358][ T9476] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 71.845365][ T9476] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 71.845372][ T9476] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 71.845379][ T9476] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 71.845407][ T9476] [ 71.845413][ T9476] Allocated by task 9476: [ 71.845425][ T9476] save_stack+0x1b/0x40 [ 71.845437][ T9476] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 71.845449][ T9476] kmem_cache_alloc_trace+0x153/0x7d0 [ 71.845458][ T9476] vc_allocate+0x1e2/0x6e0 [ 71.845467][ T9476] con_install+0x4f/0x400 [ 71.845478][ T9476] tty_init_dev+0xf5/0x460 [ 71.845486][ T9476] tty_open+0x47f/0xb30 [ 71.845498][ T9476] chrdev_open+0x219/0x5c0 [ 71.845509][ T9476] do_dentry_open+0x49e/0x1250 [ 71.845521][ T9476] path_openat+0x122a/0x3230 [ 71.845532][ T9476] do_filp_open+0x192/0x260 [ 71.845543][ T9476] do_sys_openat2+0x54c/0x740 [ 71.845555][ T9476] do_sys_open+0xc3/0x140 [ 71.845566][ T9476] do_syscall_64+0xf6/0x790 [ 71.845577][ T9476] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.845580][ T9476] [ 71.845585][ T9476] Freed by task 9483: [ 71.845595][ T9476] save_stack+0x1b/0x40 [ 71.845606][ T9476] __kasan_slab_free+0xf7/0x140 [ 71.845616][ T9476] kfree+0x109/0x2b0 [ 71.845627][ T9476] vt_disallocate_all+0x283/0x370 [ 71.845636][ T9476] vt_ioctl+0x79e/0x2450 [ 71.845648][ T9476] tty_ioctl+0xedd/0x1440 [ 71.845657][ T9476] ksys_ioctl+0x11a/0x180 [ 71.845666][ T9476] __x64_sys_ioctl+0x6f/0xb0 [ 71.845676][ T9476] do_syscall_64+0xf6/0x790 [ 71.845687][ T9476] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.845691][ T9476] [ 71.845699][ T9476] The buggy address belongs to the object at ffff88809f3d8000 [ 71.845699][ T9476] which belongs to the cache kmalloc-2k of size 2048 [ 71.845709][ T9476] The buggy address is located 264 bytes inside of [ 71.845709][ T9476] 2048-byte region [ffff88809f3d8000, ffff88809f3d8800) [ 71.845712][ T9476] The buggy address belongs to the page: [ 71.845723][ T9476] page:ffffea00027cf600 refcount:1 mapcount:0 mapping:00000000f3b08a92 index:0x0 [ 71.845732][ T9476] flags: 0xfffe0000000200(slab) [ 71.845748][ T9476] raw: 00fffe0000000200 ffffea0002a26608 ffffea00027cec48 ffff8880aa000e00 [ 71.845762][ T9476] raw: 0000000000000000 ffff88809f3d8000 0000000100000001 0000000000000000 [ 71.845766][ T9476] page dumped because: kasan: bad access detected [ 71.845769][ T9476] [ 71.845772][ T9476] Memory state around the buggy address: [ 71.845780][ T9476] ffff88809f3d8000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 71.845787][ T9476] ffff88809f3d8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 71.845795][ T9476] >ffff88809f3d8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 71.845798][ T9476] ^ [ 71.845806][ T9476] ffff88809f3d8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 71.845813][ T9476] ffff88809f3d8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 71.845817][ T9476] ================================================================== [ 71.845821][ T9476] Disabling lock debugging due to kernel taint [ 71.845849][ T9476] Kernel panic - not syncing: panic_on_warn set ... [ 71.845860][ T9476] CPU: 1 PID: 9476 Comm: syz-executor052 Tainted: G B 5.6.0-rc3-next-20200228-syzkaller #0 [ 71.845865][ T9476] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 71.845867][ T9476] Call Trace: [ 71.845878][ T9476] dump_stack+0x188/0x20d [ 71.845891][ T9476] panic+0x2e3/0x75c [ 71.845900][ T9476] ? add_taint.cold+0x16/0x16 [ 71.845909][ T9476] ? retint_kernel+0x2b/0x2b [ 71.845923][ T9476] ? trace_hardirqs_on+0x55/0x220 [ 71.845939][ T9476] ? con_shutdown+0x7f/0x90 [ 71.845949][ T9476] end_report+0x43/0x49 [ 71.845959][ T9476] ? con_shutdown+0x7f/0x90 [ 71.845968][ T9476] __kasan_report.cold+0xd/0x32 [ 71.845987][ T9476] ? con_shutdown+0x7f/0x90 [ 71.846001][ T9476] kasan_report+0xe/0x20 [ 71.846013][ T9476] con_shutdown+0x7f/0x90 [ 71.846024][ T9476] ? update_region+0x140/0x140 [ 71.846035][ T9476] release_tty+0xca/0x450 [ 71.846049][ T9476] tty_release_struct+0x37/0x50 [ 71.846062][ T9476] tty_release+0xbc7/0xe90 [ 71.846080][ T9476] ? do_tty_hangup+0x30/0x30 [ 71.846090][ T9476] __fput+0x2da/0x850 [ 71.846107][ T9476] task_work_run+0x13f/0x1b0 [ 71.846121][ T9476] do_exit+0xb53/0x2e10 [ 71.846139][ T9476] ? mm_update_next_owner+0x7a0/0x7a0 [ 71.846150][ T9476] ? up_read+0x1a8/0x750 [ 71.846161][ T9476] ? down_read_nested+0x430/0x430 [ 71.846172][ T9476] ? handle_mm_fault+0x29e/0x660 [ 71.846182][ T9476] do_group_exit+0x125/0x340 [ 71.846193][ T9476] __x64_sys_exit_group+0x3a/0x50 [ 71.846202][ T9476] do_syscall_64+0xf6/0x790 [ 71.846213][ T9476] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.846220][ T9476] RIP: 0033:0x43ff38 [ 71.846227][ T9476] Code: Bad RIP value. [ 71.846231][ T9476] RSP: 002b:00007ffd8ecdcb78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 71.846239][ T9476] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 71.846244][ T9476] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 71.846249][ T9476] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 71.846254][ T9476] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 71.846259][ T9476] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 71.847703][ T9476] Kernel Offset: disabled