[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 71.463246][ T27] audit: type=1800 audit(1584876937.747:25): pid=9375 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 71.490700][ T27] audit: type=1800 audit(1584876937.747:26): pid=9375 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 71.532927][ T27] audit: type=1800 audit(1584876937.757:27): pid=9375 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 '10.128.1.51' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 83.255772][ T9533] ================================================================== [ 83.255832][ T9533] BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 [ 83.255843][ T9533] Write of size 8 at addr ffff8880a8372108 by task syz-executor812/9533 [ 83.255846][ T9533] [ 83.255860][ T9533] CPU: 1 PID: 9533 Comm: syz-executor812 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 83.255867][ T9533] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 83.255872][ T9533] Call Trace: [ 83.255889][ T9533] dump_stack+0x188/0x20d [ 83.255903][ T9533] ? con_shutdown+0x7f/0x90 [ 83.255917][ T9533] ? con_shutdown+0x7f/0x90 [ 83.255933][ T9533] print_address_description.constprop.0.cold+0xd3/0x315 [ 83.255945][ T9533] ? con_shutdown+0x7f/0x90 [ 83.255960][ T9533] ? con_shutdown+0x7f/0x90 [ 83.255970][ T9533] __kasan_report.cold+0x1a/0x32 [ 83.255988][ T9533] ? con_shutdown+0x7f/0x90 [ 83.256006][ T9533] kasan_report+0xe/0x20 [ 83.256019][ T9533] con_shutdown+0x7f/0x90 [ 83.256031][ T9533] ? update_region+0x140/0x140 [ 83.256044][ T9533] release_tty+0xca/0x450 [ 83.256060][ T9533] tty_release_struct+0x37/0x50 [ 83.256075][ T9533] tty_release+0xbc7/0xe90 [ 83.256103][ T9533] ? do_tty_hangup+0x30/0x30 [ 83.256114][ T9533] __fput+0x2da/0x850 [ 83.256143][ T9533] task_work_run+0x13f/0x1b0 [ 83.256201][ T9533] do_exit+0xb53/0x2e10 [ 83.256230][ T9533] ? mm_update_next_owner+0x7a0/0x7a0 [ 83.256245][ T9533] ? up_read+0x1a8/0x750 [ 83.256264][ T9533] ? down_read_nested+0x430/0x430 [ 83.256283][ T9533] ? handle_mm_fault+0x29e/0x660 [ 83.256303][ T9533] do_group_exit+0x125/0x340 [ 83.256320][ T9533] __x64_sys_exit_group+0x3a/0x50 [ 83.256336][ T9533] do_syscall_64+0xf6/0x790 [ 83.256356][ T9533] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 83.256367][ T9533] RIP: 0033:0x43ff38 [ 83.256379][ T9533] 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 [ 83.256386][ T9533] RSP: 002b:00007ffe19c9eb18 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 83.256398][ T9533] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 83.256405][ T9533] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 83.256413][ T9533] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 83.256420][ T9533] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 83.256427][ T9533] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 83.256456][ T9533] [ 83.256462][ T9533] Allocated by task 9533: [ 83.256475][ T9533] save_stack+0x1b/0x40 [ 83.256487][ T9533] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 83.256499][ T9533] kmem_cache_alloc_trace+0x153/0x7d0 [ 83.256508][ T9533] vc_allocate+0x1e2/0x6e0 [ 83.256518][ T9533] con_install+0x4f/0x400 [ 83.256529][ T9533] tty_init_dev+0xf5/0x460 [ 83.256538][ T9533] tty_open+0x47f/0xb30 [ 83.256549][ T9533] chrdev_open+0x219/0x5c0 [ 83.256561][ T9533] do_dentry_open+0x49e/0x1250 [ 83.256572][ T9533] path_openat+0x122a/0x3230 [ 83.256583][ T9533] do_filp_open+0x192/0x260 [ 83.256594][ T9533] do_sys_openat2+0x54c/0x740 [ 83.256605][ T9533] do_sys_open+0xc3/0x140 [ 83.256617][ T9533] do_syscall_64+0xf6/0x790 [ 83.256628][ T9533] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 83.256632][ T9533] [ 83.256637][ T9533] Freed by task 9535: [ 83.256648][ T9533] save_stack+0x1b/0x40 [ 83.256659][ T9533] __kasan_slab_free+0xf7/0x140 [ 83.256669][ T9533] kfree+0x109/0x2b0 [ 83.256679][ T9533] vt_disallocate_all+0x283/0x370 [ 83.256688][ T9533] vt_ioctl+0x79e/0x2450 [ 83.256699][ T9533] tty_ioctl+0xedd/0x1440 [ 83.256709][ T9533] ksys_ioctl+0x11a/0x180 [ 83.256718][ T9533] __x64_sys_ioctl+0x6f/0xb0 [ 83.256729][ T9533] do_syscall_64+0xf6/0x790 [ 83.256739][ T9533] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 83.256742][ T9533] [ 83.256749][ T9533] The buggy address belongs to the object at ffff8880a8372000 [ 83.256749][ T9533] which belongs to the cache kmalloc-2k of size 2048 [ 83.256758][ T9533] The buggy address is located 264 bytes inside of [ 83.256758][ T9533] 2048-byte region [ffff8880a8372000, ffff8880a8372800) [ 83.256762][ T9533] The buggy address belongs to the page: [ 83.256773][ T9533] page:ffffea0002a0dc80 refcount:1 mapcount:0 mapping:0000000070dda3c1 index:0x0 [ 83.256782][ T9533] flags: 0xfffe0000000200(slab) [ 83.256798][ T9533] raw: 00fffe0000000200 ffffea0002a12308 ffffea0002546f88 ffff8880aa000e00 [ 83.256812][ T9533] raw: 0000000000000000 ffff8880a8372000 0000000100000001 0000000000000000 [ 83.256818][ T9533] page dumped because: kasan: bad access detected [ 83.256821][ T9533] [ 83.256825][ T9533] Memory state around the buggy address: [ 83.256835][ T9533] ffff8880a8372000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 83.256844][ T9533] ffff8880a8372080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 83.256853][ T9533] >ffff8880a8372100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 83.256858][ T9533] ^ [ 83.256867][ T9533] ffff8880a8372180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 83.256876][ T9533] ffff8880a8372200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 83.256881][ T9533] ================================================================== [ 83.256885][ T9533] Disabling lock debugging due to kernel taint [ 83.256891][ T9533] Kernel panic - not syncing: panic_on_warn set ... [ 83.256903][ T9533] CPU: 1 PID: 9533 Comm: syz-executor812 Tainted: G B 5.6.0-rc3-next-20200228-syzkaller #0 [ 83.256908][ T9533] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 83.256911][ T9533] Call Trace: [ 83.256924][ T9533] dump_stack+0x188/0x20d [ 83.256938][ T9533] panic+0x2e3/0x75c [ 83.256950][ T9533] ? add_taint.cold+0x16/0x16 [ 83.256967][ T9533] ? print_shadow_for_address+0xb8/0x114 [ 83.256978][ T9533] ? trace_hardirqs_on+0x55/0x220 [ 83.256991][ T9533] ? con_shutdown+0x7f/0x90 [ 83.257000][ T9533] end_report+0x43/0x49 [ 83.257011][ T9533] ? con_shutdown+0x7f/0x90 [ 83.257020][ T9533] __kasan_report.cold+0xd/0x32 [ 83.257034][ T9533] ? con_shutdown+0x7f/0x90 [ 83.257048][ T9533] kasan_report+0xe/0x20 [ 83.257058][ T9533] con_shutdown+0x7f/0x90 [ 83.257069][ T9533] ? update_region+0x140/0x140 [ 83.257079][ T9533] release_tty+0xca/0x450 [ 83.257093][ T9533] tty_release_struct+0x37/0x50 [ 83.257104][ T9533] tty_release+0xbc7/0xe90 [ 83.257122][ T9533] ? do_tty_hangup+0x30/0x30 [ 83.257130][ T9533] __fput+0x2da/0x850 [ 83.257147][ T9533] task_work_run+0x13f/0x1b0 [ 83.257170][ T9533] do_exit+0xb53/0x2e10 [ 83.257189][ T9533] ? mm_update_next_owner+0x7a0/0x7a0 [ 83.257200][ T9533] ? up_read+0x1a8/0x750 [ 83.257215][ T9533] ? down_read_nested+0x430/0x430 [ 83.257227][ T9533] ? handle_mm_fault+0x29e/0x660 [ 83.257240][ T9533] do_group_exit+0x125/0x340 [ 83.257253][ T9533] __x64_sys_exit_group+0x3a/0x50 [ 83.257265][ T9533] do_syscall_64+0xf6/0x790 [ 83.257278][ T9533] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 83.257287][ T9533] RIP: 0033:0x43ff38 [ 83.257298][ T9533] 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 [ 83.257305][ T9533] RSP: 002b:00007ffe19c9eb18 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 83.257314][ T9533] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 83.257321][ T9533] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 83.257328][ T9533] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 83.257334][ T9533] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 83.257340][ T9533] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 83.258712][ T9533] Kernel Offset: disabled [ 84.020797][ T9533] Rebooting in 86400 seconds..