==================================================================
BUG: KASAN: use-after-free in con_shutdown+0x85/0x90 drivers/tty/vt/vt.c:3289
Write of size 8 at addr ffff8880a830d108 by task syz-executor.2/6261

CPU: 0 PID: 6261 Comm: syz-executor.2 Not tainted 5.6.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 __asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:140
 con_shutdown+0x85/0x90 drivers/tty/vt/vt.c:3289
 release_tty+0xd3/0x470 drivers/tty/tty_io.c:1514
 tty_release_struct+0x3c/0x50 drivers/tty/tty_io.c:1629
 tty_release+0xbcb/0xe90 drivers/tty/tty_io.c:1789
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xba9/0x2f50 kernel/exit.c:801
 do_group_exit+0x135/0x360 kernel/exit.c:899
 get_signal+0x47c/0x24f0 kernel/signal.c:2734
 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c449
Code: 44 00 00 eb 42 90 c7 04 24 02 00 00 00 48 8d 44 24 30 48 89 44 24 08 48 c7 44 24 10 00 00 00 00 c7 44 24 18 08 00 00 00 e8 74 <44> 00 00 48 8b 05 15 08 c5 01 48 89 04 24 48 8d 44 24 28 48 89 44
RSP: 002b:00007faa12573cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000076bf28 RCX: 000000000045c449
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000076bf28
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000076bf2c
R13: 00007ffdc637ac1f R14: 00007faa125749c0 R15: 000000000076bf2c

Allocated by task 6261:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529
 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 vc_allocate drivers/tty/vt/vt.c:1096 [inline]
 vc_allocate+0x1fc/0x760 drivers/tty/vt/vt.c:1077
 con_install+0x52/0x410 drivers/tty/vt/vt.c:3240
 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline]
 tty_init_dev drivers/tty/tty_io.c:1341 [inline]
 tty_init_dev+0xf9/0x470 drivers/tty/tty_io.c:1318
 tty_open_by_driver drivers/tty/tty_io.c:1987 [inline]
 tty_open+0x4a5/0xbb0 drivers/tty/tty_io.c:2035
 chrdev_open+0x245/0x6b0 fs/char_dev.c:414
 do_dentry_open+0x4e6/0x1380 fs/open.c:797
 vfs_open+0xa0/0xd0 fs/open.c:914
 do_last fs/namei.c:3490 [inline]
 path_openat+0x12ee/0x3490 fs/namei.c:3607
 do_filp_open+0x192/0x260 fs/namei.c:3637
 do_sys_openat2+0x5eb/0x7e0 fs/open.c:1149
 do_sys_open+0xf2/0x180 fs/open.c:1165
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1171 [inline]
 __se_sys_open fs/open.c:1169 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1169
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6504:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 vt_disallocate_all+0x2bd/0x3e0 drivers/tty/vt/vt_ioctl.c:323
 vt_ioctl+0xc38/0x26c0 drivers/tty/vt/vt_ioctl.c:816
 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x123/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a830d000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 264 bytes inside of
 2048-byte region [ffff8880a830d000, ffff8880a830d800)
The buggy address belongs to the page:
page:ffffea0002a0c340 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002a27d08 ffffea00024a42c8 ffff8880aa400e00
raw: 0000000000000000 ffff8880a830d000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a830d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a830d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a830d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8880a830d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a830d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================