IPVS: ftp: loaded support on port[0] = 21
==================================================================
BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 drivers/tty/vt/vt.c:3262
Write of size 8 at addr ffff8880966ecec8 by task syz-executor832/8170

CPU: 0 PID: 8170 Comm: syz-executor832 Not tainted 4.19.109-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+0x188/0x20d lib/dump_stack.c:118
 print_address_description.cold+0x7c/0x212 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x88/0x2b9 mm/kasan/report.c:396
 con_shutdown+0x7f/0x90 drivers/tty/vt/vt.c:3262
 release_tty+0xda/0x4c0 drivers/tty/tty_io.c:1509
 tty_release_struct+0x37/0x50 drivers/tty/tty_io.c:1624
 tty_release+0xbc7/0xe90 drivers/tty/tty_io.c:1784
 __fput+0x2cd/0x890 fs/file_table.c:278
 task_work_run+0x13f/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x25a/0x2b0 arch/x86/entry/common.c:167
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
 do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x401130
Code: 01 f0 ff ff 0f 83 20 0c 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d 9d 25 2d 00 00 75 14 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 f4 0b 00 00 c3 48 83 ec 08 e8 5a 01 00 00
RSP: 002b:00007fff2c560028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000401130
RDX: 0000000000000000 RSI: 0000000000005608 RDI: 0000000000000003
RBP: 000000000000e758 R08: 000000000000000e R09: 0000000100000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004021b0
R13: 0000000000402240 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 8170:
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:531
 kmem_cache_alloc_trace+0x14d/0x7a0 mm/slab.c:3625
 kmalloc include/linux/slab.h:515 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 vc_allocate drivers/tty/vt/vt.c:1099 [inline]
 vc_allocate+0x1db/0x6d0 drivers/tty/vt/vt.c:1080
 con_install+0x4f/0x400 drivers/tty/vt/vt.c:3213
 tty_driver_install_tty drivers/tty/tty_io.c:1226 [inline]
 tty_init_dev drivers/tty/tty_io.c:1339 [inline]
 tty_init_dev+0xee/0x450 drivers/tty/tty_io.c:1316
 tty_open_by_driver drivers/tty/tty_io.c:1981 [inline]
 tty_open+0x4b0/0xb00 drivers/tty/tty_io.c:2029
 chrdev_open+0x219/0x5c0 fs/char_dev.c:423
 do_dentry_open+0x4a8/0x1160 fs/open.c:796
 do_last fs/namei.c:3421 [inline]
 path_openat+0x1031/0x4200 fs/namei.c:3537
 do_filp_open+0x1a1/0x280 fs/namei.c:3567
 do_sys_open+0x3c0/0x500 fs/open.c:1088
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8172:
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/kasan.c:521
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xce/0x220 mm/slab.c:3822
 vt_disallocate_all+0x293/0x3b0 drivers/tty/vt/vt_ioctl.c:323
 vt_ioctl+0xb79/0x2310 drivers/tty/vt/vt_ioctl.c:816
 tty_ioctl+0x7a1/0x1420 drivers/tty/tty_io.c:2669
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcda/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880966ecdc0
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 264 bytes inside of
 2048-byte region [ffff8880966ecdc0, ffff8880966ed5c0)
The buggy address belongs to the page:
page:ffffea000259bb00 count:1 mapcount:0 mapping:ffff88812c3dcc40 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea0002546a88 ffffea0002581388 ffff88812c3dcc40
raw: 0000000000000000 ffff8880966ec540 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880966ecd80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8880966ece00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880966ece80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8880966ecf00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880966ecf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================