[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 34.580522] random: sshd: uninitialized urandom read (32 bytes read) [ 35.007215] kauditd_printk_skb: 10 callbacks suppressed [ 35.007222] audit: type=1400 audit(1581255796.890:35): avc: denied { map } for pid=7217 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 [ 35.096861] random: sshd: uninitialized urandom read (32 bytes read) [ 35.861233] random: sshd: uninitialized urandom read (32 bytes read) [ 36.088187] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.158' (ECDSA) to the list of known hosts. [ 41.636651] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program [ 41.752261] audit: type=1400 audit(1581255803.640:36): avc: denied { map } for pid=7230 comm="syz-executor228" path="/root/syz-executor228633445" dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 41.800318] ================================================================== [ 41.800346] BUG: KASAN: use-after-free in con_shutdown+0x85/0x90 [ 41.800352] Write of size 8 at addr ffff8880997e5208 by task syz-executor228/7237 [ 41.800354] [ 41.800361] CPU: 0 PID: 7237 Comm: syz-executor228 Not tainted 4.14.170-syzkaller #0 [ 41.800366] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.800368] Call Trace: [ 41.800379] dump_stack+0x142/0x197 [ 41.800388] ? con_shutdown+0x85/0x90 [ 41.800397] print_address_description.cold+0x7c/0x1dc [ 41.800405] ? con_shutdown+0x85/0x90 [ 41.800412] kasan_report.cold+0xa9/0x2af [ 41.800419] ? set_palette+0x140/0x140 [ 41.800428] __asan_report_store8_noabort+0x17/0x20 [ 41.800435] con_shutdown+0x85/0x90 [ 41.800443] release_tty+0xbf/0x7c0 [ 41.800452] tty_release_struct+0x3c/0x50 [ 41.800461] tty_release+0xaa3/0xd60 [ 41.800474] ? tty_release_struct+0x50/0x50 [ 41.800481] __fput+0x275/0x7a0 [ 41.800493] ____fput+0x16/0x20 [ 41.800503] task_work_run+0x114/0x190 [ 41.800516] do_exit+0xa1a/0x2cd0 [ 41.800538] ? mm_update_next_owner+0x5d0/0x5d0 [ 41.800550] ? up_read+0x1a/0x40 [ 41.800558] ? __do_page_fault+0x358/0xb80 [ 41.800567] do_group_exit+0x111/0x330 [ 41.800577] SyS_exit_group+0x1d/0x20 [ 41.800584] ? do_group_exit+0x330/0x330 [ 41.800592] do_syscall_64+0x1e8/0x640 [ 41.800600] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 41.800614] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.800620] RIP: 0033:0x43ff38 [ 41.800624] RSP: 002b:00007ffefce928b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 41.800633] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 41.800637] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 41.800642] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 41.800646] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 41.800651] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 41.800664] [ 41.800668] Allocated by task 7237: [ 41.800676] save_stack_trace+0x16/0x20 [ 41.800682] save_stack+0x45/0xd0 [ 41.800687] kasan_kmalloc+0xce/0xf0 [ 41.800693] kmem_cache_alloc_trace+0x152/0x790 [ 41.800700] vc_allocate+0x148/0x580 [ 41.800707] con_install+0x52/0x400 [ 41.800713] tty_init_dev+0xea/0x3a0 [ 41.800719] tty_open+0x414/0xa10 [ 41.800726] chrdev_open+0x207/0x590 [ 41.800733] do_dentry_open+0x73b/0xeb0 [ 41.800739] vfs_open+0x105/0x220 [ 41.800746] path_openat+0x917/0x3e50 [ 41.800752] do_filp_open+0x18e/0x250 [ 41.800758] do_sys_open+0x2c5/0x430 [ 41.800765] SyS_open+0x2d/0x40 [ 41.800771] do_syscall_64+0x1e8/0x640 [ 41.800778] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.800780] [ 41.800784] Freed by task 7238: [ 41.800789] save_stack_trace+0x16/0x20 [ 41.800795] save_stack+0x45/0xd0 [ 41.800801] kasan_slab_free+0x75/0xc0 [ 41.800806] kfree+0xcc/0x270 [ 41.800812] vt_disallocate_all+0x286/0x380 [ 41.800817] vt_ioctl+0x76b/0x2170 [ 41.800829] tty_ioctl+0x841/0x1320 [ 41.800835] do_vfs_ioctl+0x7ae/0x1060 [ 41.800841] SyS_ioctl+0x8f/0xc0 [ 41.800847] do_syscall_64+0x1e8/0x640 [ 41.800853] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.800855] [ 41.800860] The buggy address belongs to the object at ffff8880997e5100 [ 41.800860] which belongs to the cache kmalloc-2048 of size 2048 [ 41.800866] The buggy address is located 264 bytes inside of [ 41.800866] 2048-byte region [ffff8880997e5100, ffff8880997e5900) [ 41.800869] The buggy address belongs to the page: [ 41.800874] page:ffffea000265f900 count:1 mapcount:0 mapping:ffff8880997e4000 index:0x0 compound_mapcount: 0 [ 41.800888] flags: 0xfffe0000008100(slab|head) [ 41.800897] raw: 00fffe0000008100 ffff8880997e4000 0000000000000000 0000000100000003 [ 41.800904] raw: ffffea000264c4a0 ffffea00026430a0 ffff8880aa800c40 0000000000000000 [ 41.800907] page dumped because: kasan: bad access detected [ 41.800910] [ 41.800912] Memory state around the buggy address: [ 41.800918] ffff8880997e5100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.800923] ffff8880997e5180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.800928] >ffff8880997e5200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.800931] ^ [ 41.800936] ffff8880997e5280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.800941] ffff8880997e5300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.800944] ================================================================== [ 41.800946] Disabling lock debugging due to kernel taint [ 41.800971] Kernel panic - not syncing: panic_on_warn set ... [ 41.800971] [ 41.800977] CPU: 0 PID: 7237 Comm: syz-executor228 Tainted: G B 4.14.170-syzkaller #0 [ 41.800980] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.800982] Call Trace: [ 41.800989] dump_stack+0x142/0x197 [ 41.800996] ? con_shutdown+0x85/0x90 [ 41.801001] panic+0x1f9/0x42d [ 41.801006] ? add_taint.cold+0x16/0x16 [ 41.801016] kasan_end_report+0x47/0x4f [ 41.801021] kasan_report.cold+0x130/0x2af [ 41.801028] ? set_palette+0x140/0x140 [ 41.801034] __asan_report_store8_noabort+0x17/0x20 [ 41.801040] con_shutdown+0x85/0x90 [ 41.801046] release_tty+0xbf/0x7c0 [ 41.801053] tty_release_struct+0x3c/0x50 [ 41.801059] tty_release+0xaa3/0xd60 [ 41.801068] ? tty_release_struct+0x50/0x50 [ 41.801073] __fput+0x275/0x7a0 [ 41.801081] ____fput+0x16/0x20 [ 41.801087] task_work_run+0x114/0x190 [ 41.801094] do_exit+0xa1a/0x2cd0 [ 41.801103] ? mm_update_next_owner+0x5d0/0x5d0 [ 41.801111] ? up_read+0x1a/0x40 [ 41.801116] ? __do_page_fault+0x358/0xb80 [ 41.801123] do_group_exit+0x111/0x330 [ 41.801130] SyS_exit_group+0x1d/0x20 [ 41.801135] ? do_group_exit+0x330/0x330 [ 41.801141] do_syscall_64+0x1e8/0x640 [ 41.801147] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 41.801155] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.801159] RIP: 0033:0x43ff38 [ 41.801162] RSP: 002b:00007ffefce928b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 41.801168] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff38 [ 41.801172] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 41.801175] RBP: 00000000004bf950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 41.801179] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 41.801182] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 41.802463] Kernel Offset: disabled [ 42.417605] Rebooting in 86400 seconds..