[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 33.532812] random: sshd: uninitialized urandom read (32 bytes read) [ 33.820376] kauditd_printk_skb: 10 callbacks suppressed [ 33.820383] audit: type=1400 audit(1575760999.906:35): avc: denied { map } for pid=6989 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 [ 33.878365] random: sshd: uninitialized urandom read (32 bytes read) [ 34.426527] random: sshd: uninitialized urandom read (32 bytes read) [ 56.989043] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.101' (ECDSA) to the list of known hosts. [ 62.621810] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 62.752828] audit: type=1400 audit(1575761028.836:36): avc: denied { map } for pid=7002 comm="syz-executor322" path="/root/syz-executor322229295" dev="sda1" ino=1426 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 executing program [ 62.816140] ================================================================== [ 62.823763] BUG: KASAN: use-after-free in __cancel_work_timer+0x40f/0x480 [ 62.830863] Read of size 8 at addr ffff888095d27388 by task syz-executor322/7012 [ 62.838519] [ 62.840158] CPU: 0 PID: 7012 Comm: syz-executor322 Not tainted 4.14.158-syzkaller #0 [ 62.848252] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 62.858166] Call Trace: [ 62.860768] dump_stack+0x142/0x197 [ 62.864411] ? __cancel_work_timer+0x40f/0x480 [ 62.869224] print_address_description.cold+0x7c/0x1dc [ 62.874511] ? __cancel_work_timer+0x40f/0x480 [ 62.879171] kasan_report.cold+0xa9/0x2af [ 62.883516] __asan_report_load8_noabort+0x14/0x20 [ 62.888633] __cancel_work_timer+0x40f/0x480 [ 62.893057] ? cancel_delayed_work+0x20/0x20 [ 62.897478] ? trace_hardirqs_on_caller+0x400/0x590 [ 62.902583] ? trace_hardirqs_on+0xd/0x10 [ 62.906723] ? console_unlock+0xa4a/0xed0 [ 62.910887] cancel_work_sync+0x18/0x20 [ 62.914892] tty_buffer_cancel_work+0x16/0x20 [ 62.919596] release_tty+0x3f4/0x7c0 [ 62.923311] tty_release_struct+0x3c/0x50 [ 62.927447] tty_release+0xaa3/0xd60 [ 62.931250] ? tty_release_struct+0x50/0x50 [ 62.935557] __fput+0x275/0x7a0 [ 62.938833] ____fput+0x16/0x20 [ 62.942107] task_work_run+0x114/0x190 [ 62.945980] do_exit+0x7be/0x2c80 [ 62.949422] ? mm_update_next_owner+0x5d0/0x5d0 [ 62.954186] ? up_read+0x1a/0x40 [ 62.957534] ? __do_page_fault+0x358/0xb80 [ 62.961752] do_group_exit+0x111/0x330 [ 62.965624] SyS_exit_group+0x1d/0x20 [ 62.969404] ? do_group_exit+0x330/0x330 [ 62.973471] do_syscall_64+0x1e8/0x640 [ 62.977344] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 62.982177] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 62.987537] RIP: 0033:0x43ff38 [ 62.990712] RSP: 002b:00007ffe4e00bd08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 62.998489] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 63.005740] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 63.013202] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 63.020477] R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000001 [ 63.027743] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 63.035094] [ 63.036719] Allocated by task 7012: [ 63.040333] save_stack_trace+0x16/0x20 [ 63.044290] save_stack+0x45/0xd0 [ 63.047722] kasan_kmalloc+0xce/0xf0 [ 63.051417] kmem_cache_alloc_trace+0x152/0x790 [ 63.056219] vc_allocate+0x148/0x580 [ 63.060098] con_install+0x52/0x400 [ 63.063715] tty_init_dev+0xea/0x3a0 [ 63.067420] tty_open+0x414/0xa10 [ 63.071145] chrdev_open+0x207/0x590 [ 63.074976] do_dentry_open+0x73b/0xeb0 [ 63.079056] vfs_open+0x105/0x220 [ 63.082604] path_openat+0x8bd/0x3f70 [ 63.086394] do_filp_open+0x18e/0x250 [ 63.090197] do_sys_open+0x2c5/0x430 [ 63.093915] SyS_open+0x2d/0x40 [ 63.097183] do_syscall_64+0x1e8/0x640 [ 63.101065] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.106788] [ 63.108414] Freed by task 7017: [ 63.111701] save_stack_trace+0x16/0x20 [ 63.115663] save_stack+0x45/0xd0 [ 63.119125] kasan_slab_free+0x75/0xc0 [ 63.123239] kfree+0xcc/0x270 [ 63.126342] vt_disallocate_all+0x286/0x380 [ 63.130752] vt_ioctl+0x76b/0x2170 [ 63.134288] tty_ioctl+0x841/0x1320 [ 63.137900] do_vfs_ioctl+0x7ae/0x1060 [ 63.141770] SyS_ioctl+0x8f/0xc0 [ 63.145134] do_syscall_64+0x1e8/0x640 [ 63.149276] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.154575] [ 63.156192] The buggy address belongs to the object at ffff888095d27380 [ 63.156192] which belongs to the cache kmalloc-2048 of size 2048 [ 63.169766] The buggy address is located 8 bytes inside of [ 63.169766] 2048-byte region [ffff888095d27380, ffff888095d27b80) [ 63.182123] The buggy address belongs to the page: [ 63.187060] page:ffffea0002574980 count:1 mapcount:0 mapping:ffff888095d26280 index:0x0 compound_mapcount: 0 [ 63.197354] flags: 0xfffe0000008100(slab|head) [ 63.201944] raw: 00fffe0000008100 ffff888095d26280 0000000000000000 0000000100000003 [ 63.209935] raw: ffffea00022aca20 ffffea0002071520 ffff8880aa800c40 0000000000000000 [ 63.217793] page dumped because: kasan: bad access detected [ 63.223750] [ 63.225387] Memory state around the buggy address: [ 63.230309] ffff888095d27280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.237648] ffff888095d27300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 63.244991] >ffff888095d27380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.252342] ^ [ 63.255962] ffff888095d27400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.263414] ffff888095d27480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.270868] ================================================================== [ 63.278919] Disabling lock debugging due to kernel taint [ 63.285736] Kernel panic - not syncing: panic_on_warn set ... [ 63.285736] [ 63.293125] CPU: 0 PID: 7012 Comm: syz-executor322 Tainted: G B 4.14.158-syzkaller #0 [ 63.302644] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 63.312189] Call Trace: [ 63.314855] dump_stack+0x142/0x197 [ 63.319073] ? __cancel_work_timer+0x40f/0x480 [ 63.323974] panic+0x1f9/0x42d [ 63.327243] ? add_taint.cold+0x16/0x16 [ 63.331303] ? ___preempt_schedule+0x16/0x18 [ 63.335706] kasan_end_report+0x47/0x4f [ 63.339673] kasan_report.cold+0x130/0x2af [ 63.343905] __asan_report_load8_noabort+0x14/0x20 [ 63.348955] __cancel_work_timer+0x40f/0x480 [ 63.353449] ? cancel_delayed_work+0x20/0x20 [ 63.357840] ? trace_hardirqs_on_caller+0x400/0x590 [ 63.363398] ? trace_hardirqs_on+0xd/0x10 [ 63.367617] ? console_unlock+0xa4a/0xed0 [ 63.371765] cancel_work_sync+0x18/0x20 [ 63.375865] tty_buffer_cancel_work+0x16/0x20 [ 63.380497] release_tty+0x3f4/0x7c0 [ 63.384264] tty_release_struct+0x3c/0x50 [ 63.388609] tty_release+0xaa3/0xd60 [ 63.392447] ? tty_release_struct+0x50/0x50 [ 63.396762] __fput+0x275/0x7a0 [ 63.400117] ____fput+0x16/0x20 [ 63.403465] task_work_run+0x114/0x190 [ 63.407336] do_exit+0x7be/0x2c80 [ 63.410809] ? mm_update_next_owner+0x5d0/0x5d0 [ 63.415818] ? up_read+0x1a/0x40 [ 63.419283] ? __do_page_fault+0x358/0xb80 [ 63.423612] do_group_exit+0x111/0x330 [ 63.427831] SyS_exit_group+0x1d/0x20 [ 63.431635] ? do_group_exit+0x330/0x330 [ 63.435684] do_syscall_64+0x1e8/0x640 [ 63.439854] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 63.444776] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.449998] RIP: 0033:0x43ff38 [ 63.453264] RSP: 002b:00007ffe4e00bd08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 63.461044] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 63.468510] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 63.475850] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 63.483349] R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000001 [ 63.490782] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 63.499662] Kernel Offset: disabled [ 63.503387] Rebooting in 86400 seconds..