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BUG: KASAN: use-after-free in con_shutdown+0x61/0x80 drivers/tty/vt/vt.c:3287
Write of size 8 at addr ffff8880a9061108 by task syz-executor.5/21169

CPU: 1 PID: 21169 Comm: syz-executor.5 Not tainted 5.6.0-rc7-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+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x74/0x5c0 mm/kasan/report.c:374
 __kasan_report+0x14b/0x1c0 mm/kasan/report.c:506
 kasan_report+0x25/0x50 mm/kasan/common.c:641
 con_shutdown+0x61/0x80 drivers/tty/vt/vt.c:3287
 release_tty+0xb9/0x530 drivers/tty/tty_io.c:1514
 tty_release_struct+0xb8/0xd0 drivers/tty/tty_io.c:1625
 tty_release+0xe23/0x1100 drivers/tty/tty_io.c:1785
 __fput+0x2d8/0x730 fs/file_table.c:280
 task_work_run+0x176/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:164 [inline]
 prepare_exit_to_usermode+0x48e/0x600 arch/x86/entry/common.c:195
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4163e1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffc27a31720 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004163e1
RDX: 0000001b31120000 RSI: 00000000000001e1 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00000000d09361e1 R09: 00000000d09361e5
R10: 00007ffc27a31800 R11: 0000000000000293 R12: 000000000076bf00
R13: 0000000000770108 R14: 000000000003a7bb R15: 000000000076bf0c

Allocated by task 11290:
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:515
 kmem_cache_alloc_trace+0x234/0x300 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 vc_allocate+0x148/0x5b0 drivers/tty/vt/vt.c:1096
 con_install+0x48/0x460 drivers/tty/vt/vt.c:3238
 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline]
 tty_init_dev+0xc6/0x4c0 drivers/tty/tty_io.c:1341
 tty_open_by_driver drivers/tty/tty_io.c:1983 [inline]
 tty_open+0x7cd/0xca0 drivers/tty/tty_io.c:2031
 chrdev_open+0x498/0x580 fs/char_dev.c:414
 do_dentry_open+0x828/0x10a0 fs/open.c:797
 do_last fs/namei.c:3490 [inline]
 path_openat+0x13b5/0x40d0 fs/namei.c:3607
 do_filp_open+0x191/0x3a0 fs/namei.c:3637
 do_sys_openat2+0x448/0x6c0 fs/open.c:1146
 do_sys_open fs/open.c:1162 [inline]
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1168 [inline]
 __se_sys_open fs/open.c:1166 [inline]
 __x64_sys_open+0x1af/0x1e0 fs/open.c:1166
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 21213:
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:476
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 vt_disallocate_all drivers/tty/vt/vt_ioctl.c:323 [inline]
 vt_ioctl+0x229d/0x3a30 drivers/tty/vt/vt_ioctl.c:816
 tty_ioctl+0xee6/0x15c0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl fs/ioctl.c:763 [inline]
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a9061000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 264 bytes inside of
 2048-byte region [ffff8880a9061000, ffff8880a9061800)
The buggy address belongs to the page:
page:ffffea0002a41840 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002505d48 ffffea00028bce08 ffff8880aa400e00
raw: 0000000000000000 ffff8880a9061000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a9061000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a9061080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a9061100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8880a9061180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a9061200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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