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BUG: KASAN: use-after-free in fbcon_cursor+0x8d7/0xc00 drivers/video/fbdev/core/fbcon.c:1389
Read of size 2 at addr ffff8880562324e0 by task syz-executor.5/3958

CPU: 1 PID: 3958 Comm: syz-executor.5 Not tainted 5.7.0-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+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x74/0x5c0 mm/kasan/report.c:382
 __kasan_report+0x103/0x1a0 mm/kasan/report.c:511
 kasan_report+0x4d/0x80 mm/kasan/common.c:625

Allocated by task 671:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x24b/0x330 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 kzalloc+0x1d/0x40 include/linux/slab.h:669
 vc_do_resize+0x2a0/0x1ce0 drivers/tty/vt/vt.c:1212
 fbcon_do_set_font+0xb34/0x1220 drivers/video/fbdev/core/fbcon.c:2608
 fbcon_set_font+0x782/0x970 drivers/video/fbdev/core/fbcon.c:2705
 con_font_set drivers/tty/vt/vt.c:4566 [inline]
 con_font_op+0xebc/0x1630 drivers/tty/vt/vt.c:4631
 vt_ioctl+0x179d/0x3eb0 drivers/tty/vt/vt_ioctl.c:265
 tty_ioctl+0xee4/0x15c0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl fs/ioctl.c:771 [inline]
 __do_sys_ioctl fs/ioctl.c:780 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:778
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 3958:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0x125/0x190 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 vc_do_resize+0xf63/0x1ce0 drivers/tty/vt/vt.c:1286
 vt_ioctl+0x3178/0x3eb0 drivers/tty/vt/vt_ioctl.c:901
 tty_ioctl+0xee4/0x15c0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl fs/ioctl.c:771 [inline]
 __do_sys_ioctl fs/ioctl.c:780 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:778
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff888056230000
 which belongs to the cache kmalloc-16k of size 16384
The buggy address is located 9440 bytes inside of
 16384-byte region [ffff888056230000, ffff888056234000)
The buggy address belongs to the page:
page:ffffea0001588c00 refcount:1 mapcount:0 mapping:0000000092ad5470 index:0x0 head:ffffea0001588c00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0002225408 ffffea00013b0408 ffff8880aa402380
raw: 0000000000000000 ffff888056230000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888056232380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888056232400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888056232480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888056232500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888056232580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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