[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 56.326603][ T23] audit: type=1800 audit(1581684587.263:25): pid=8722 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 56.351404][ T23] audit: type=1800 audit(1581684587.263:26): pid=8722 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 56.402255][ T23] audit: type=1800 audit(1581684587.263:27): pid=8722 uid=0 auid=4294967295 ses=4294967295 subj=_ 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 '10.128.10.25' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 74.117437][ T8994] ================================================================== [ 74.117481][ T8994] BUG: KASAN: use-after-free in n_tty_receive_buf_common+0x1f95/0x30b0 [ 74.117490][ T8994] Read of size 1 at addr ffff88809297a402 by task syz-executor717/8994 [ 74.117493][ T8994] [ 74.117503][ T8994] CPU: 1 PID: 8994 Comm: syz-executor717 Not tainted 5.6.0-rc1-syzkaller #0 [ 74.117508][ T8994] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 74.117512][ T8994] Call Trace: [ 74.117524][ T8994] dump_stack+0x1fb/0x318 [ 74.117546][ T8994] print_address_description+0x74/0x5c0 [ 74.185260][ T8994] ? vprintk_default+0x28/0x30 [ 74.185275][ T8994] ? vprintk_func+0x158/0x170 [ 74.185288][ T8994] ? printk+0x62/0x8d [ 74.185311][ T8994] __kasan_report+0x149/0x1c0 [ 74.205294][ T8994] ? n_tty_receive_buf_common+0x1f95/0x30b0 [ 74.205311][ T8994] kasan_report+0x26/0x50 [ 74.205326][ T8994] __asan_report_load1_noabort+0x14/0x20 [ 74.205334][ T8994] n_tty_receive_buf_common+0x1f95/0x30b0 [ 74.205353][ T8994] ? mutex_optimistic_spin+0x32a/0x470 [ 74.205403][ T8994] n_tty_receive_buf2+0x33/0x40 [ 74.205414][ T8994] ? n_tty_write_wakeup+0x50/0x50 [ 74.205426][ T8994] tty_ldisc_receive_buf+0x9f/0x170 [ 74.205477][ T8994] paste_selection+0x2ef/0x400 [ 74.205497][ T8994] ? do_task_dead+0xc0/0xc0 [ 74.205514][ T8994] tioclinux+0x121/0x530 [ 74.266453][ T8994] vt_ioctl+0x3f1/0x3a70 [ 74.266483][ T8994] ? rcu_lock_release+0x9/0x30 [ 74.266506][ T8994] ? tomoyo_path_number_perm+0x58f/0x690 [ 74.266544][ T8994] ? tty_jobctrl_ioctl+0x1ea/0xc00 [ 74.266573][ T8994] tty_ioctl+0xee6/0x15c0 [ 74.266601][ T8994] ? tomoyo_file_ioctl+0x23/0x30 [ 74.266615][ T8994] ? tty_do_resize+0x180/0x180 [ 74.266631][ T8994] __se_sys_ioctl+0x113/0x190 [ 74.266648][ T8994] __x64_sys_ioctl+0x7b/0x90 [ 74.266664][ T8994] do_syscall_64+0xf7/0x1c0 [ 74.266684][ T8994] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.266693][ T8994] RIP: 0033:0x446839 [ 74.266704][ T8994] Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 74.266710][ T8994] RSP: 002b:00007f3d11da9db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 74.266724][ T8994] RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446839 [ 74.266730][ T8994] RDX: 0000000020000040 RSI: 000000000000541c RDI: 0000000000000004 [ 74.266736][ T8994] RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000 [ 74.266746][ T8994] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c [ 74.266752][ T8994] R13: 00007ffc17de946f R14: 00007f3d11daa9c0 R15: 0000000000000001 [ 74.266778][ T8994] [ 74.266784][ T8994] Allocated by task 8995: [ 74.266794][ T8994] __kasan_kmalloc+0x118/0x1c0 [ 74.266801][ T8994] kasan_kmalloc+0x9/0x10 [ 74.266807][ T8994] __kmalloc+0x254/0x340 [ 74.266816][ T8994] set_selection_kernel+0xea3/0x1880 [ 74.266824][ T8994] set_selection_user+0x63/0x80 [ 74.266831][ T8994] tioclinux+0x103/0x530 [ 74.266838][ T8994] vt_ioctl+0x3f1/0x3a70 [ 74.266845][ T8994] tty_ioctl+0xee6/0x15c0 [ 74.266852][ T8994] __se_sys_ioctl+0x113/0x190 [ 74.266860][ T8994] __x64_sys_ioctl+0x7b/0x90 [ 74.266868][ T8994] do_syscall_64+0xf7/0x1c0 [ 74.266877][ T8994] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.266880][ T8994] [ 74.266884][ T8994] Freed by task 8998: [ 74.266892][ T8994] __kasan_slab_free+0x12e/0x1e0 [ 74.266899][ T8994] kasan_slab_free+0xe/0x10 [ 74.266910][ T8994] kfree+0x10d/0x220 [ 74.494546][ T8994] set_selection_kernel+0xec8/0x1880 [ 74.494554][ T8994] set_selection_user+0x63/0x80 [ 74.494560][ T8994] tioclinux+0x103/0x530 [ 74.494567][ T8994] vt_ioctl+0x3f1/0x3a70 [ 74.494575][ T8994] tty_ioctl+0xee6/0x15c0 [ 74.494583][ T8994] __se_sys_ioctl+0x113/0x190 [ 74.494590][ T8994] __x64_sys_ioctl+0x7b/0x90 [ 74.494600][ T8994] do_syscall_64+0xf7/0x1c0 [ 74.494612][ T8994] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.494615][ T8994] [ 74.494624][ T8994] The buggy address belongs to the object at ffff88809297a400 [ 74.494624][ T8994] which belongs to the cache kmalloc-512 of size 512 [ 74.494633][ T8994] The buggy address is located 2 bytes inside of [ 74.494633][ T8994] 512-byte region [ffff88809297a400, ffff88809297a600) [ 74.494638][ T8994] The buggy address belongs to the page: [ 74.494648][ T8994] page:ffffea00024a5e80 refcount:1 mapcount:0 mapping:ffff8880aa400a80 index:0x0 [ 74.494655][ T8994] flags: 0xfffe0000000200(slab) [ 74.494667][ T8994] raw: 00fffe0000000200 ffffea00022b36c8 ffffea000257c888 ffff8880aa400a80 [ 74.494677][ T8994] raw: 0000000000000000 ffff88809297a000 0000000100000004 0000000000000000 [ 74.494681][ T8994] page dumped because: kasan: bad access detected [ 74.494684][ T8994] [ 74.494687][ T8994] Memory state around the buggy address: [ 74.494694][ T8994] ffff88809297a300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 74.494700][ T8994] ffff88809297a380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 74.494707][ T8994] >ffff88809297a400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.494715][ T8994] ^ [ 74.663478][ T8994] ffff88809297a480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.663490][ T8994] ffff88809297a500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 74.663493][ T8994] ================================================================== [ 74.663497][ T8994] Disabling lock debugging due to kernel taint [ 74.664300][ T8994] Kernel panic - not syncing: panic_on_warn set ... [ 74.704251][ T8994] CPU: 1 PID: 8994 Comm: syz-executor717 Tainted: G B 5.6.0-rc1-syzkaller #0 [ 74.704256][ T8994] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 74.704259][ T8994] Call Trace: [ 74.704277][ T8994] dump_stack+0x1fb/0x318 [ 74.704290][ T8994] panic+0x264/0x7a9 [ 74.704299][ T8994] ? __kasan_report+0x193/0x1c0 [ 74.704308][ T8994] ? trace_hardirqs_on+0x34/0x80 [ 74.704316][ T8994] ? __kasan_report+0x193/0x1c0 [ 74.704329][ T8994] __kasan_report+0x1b9/0x1c0 [ 74.757829][ T8994] ? n_tty_receive_buf_common+0x1f95/0x30b0 [ 74.757841][ T8994] kasan_report+0x26/0x50 [ 74.757855][ T8994] __asan_report_load1_noabort+0x14/0x20 [ 74.775051][ T8994] n_tty_receive_buf_common+0x1f95/0x30b0 [ 74.775066][ T8994] ? mutex_optimistic_spin+0x32a/0x470 [ 74.775092][ T8994] n_tty_receive_buf2+0x33/0x40 [ 74.775100][ T8994] ? n_tty_write_wakeup+0x50/0x50 [ 74.775108][ T8994] tty_ldisc_receive_buf+0x9f/0x170 [ 74.775123][ T8994] paste_selection+0x2ef/0x400 [ 74.808519][ T8994] ? do_task_dead+0xc0/0xc0 [ 74.808532][ T8994] tioclinux+0x121/0x530 [ 74.808542][ T8994] vt_ioctl+0x3f1/0x3a70 [ 74.808561][ T8994] ? rcu_lock_release+0x9/0x30 [ 74.827281][ T8994] ? tomoyo_path_number_perm+0x58f/0x690 [ 74.827305][ T8994] ? tty_jobctrl_ioctl+0x1ea/0xc00 [ 74.827322][ T8994] tty_ioctl+0xee6/0x15c0 [ 74.842837][ T8994] ? tomoyo_file_ioctl+0x23/0x30 [ 74.842850][ T8994] ? tty_do_resize+0x180/0x180 [ 74.842861][ T8994] __se_sys_ioctl+0x113/0x190 [ 74.842872][ T8994] __x64_sys_ioctl+0x7b/0x90 [ 74.842884][ T8994] do_syscall_64+0xf7/0x1c0 [ 74.842897][ T8994] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.842905][ T8994] RIP: 0033:0x446839 [ 74.842915][ T8994] Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 74.842919][ T8994] RSP: 002b:00007f3d11da9db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 74.842928][ T8994] RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446839 [ 74.842933][ T8994] RDX: 0000000020000040 RSI: 000000000000541c RDI: 0000000000000004 [ 74.842937][ T8994] RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000 [ 74.842942][ T8994] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c [ 74.842947][ T8994] R13: 00007ffc17de946f R14: 00007f3d11daa9c0 R15: 0000000000000001 [ 74.845203][ T8994] Kernel Offset: disabled [ 74.960736][ T8994] Rebooting in 86400 seconds..