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BUG: KASAN: use-after-free in fbcon_cursor+0x409/0x570 drivers/video/fbdev/core/fbcon.c:1380
Read of size 2 at addr ffff888099615e4c by task syz-executor.5/10112

CPU: 1 PID: 10112 Comm: syz-executor.5 Not tainted 5.5.0-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+0x12d/0x187 lib/dump_stack.c:118
 print_address_description.constprop.8.cold.10+0x9/0x31d mm/kasan/report.c:374
 __kasan_report.cold.11+0x1b/0x3a mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:639
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/generic_report.c:133
 fbcon_cursor+0x409/0x570 drivers/video/fbdev/core/fbcon.c:1380
 fbcon_scrolldelta+0x51f/0xf00 drivers/video/fbdev/core/fbcon.c:2877
 fbcon_set_origin+0x16/0x20 drivers/video/fbdev/core/fbcon.c:2928
 set_origin+0xcc/0x390 drivers/tty/vt/vt.c:919
 vc_do_resize+0x90b/0x12d0 drivers/tty/vt/vt.c:1264
 vc_resize+0x3d/0x60 drivers/tty/vt/vt.c:1304
 vt_ioctl+0x36e/0x21f0 drivers/tty/vt/vt_ioctl.c:840
 tty_ioctl+0x45b/0x12f0 drivers/tty/tty_io.c:2660
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x196/0x1190 fs/ioctl.c:732
 ksys_ioctl+0x62/0x90 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:754
 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a909
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4a5b6cac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a909
RDX: 0000000020000000 RSI: 0000000000005609 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4a5b6cb6d4
R13: 00000000004c7009 R14: 00000000004dd670 R15: 00000000ffffffff

Allocated by task 10063:
 save_stack+0x21/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc.constprop.17+0xc7/0xd0 mm/kasan/common.c:513
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x164/0x790 mm/slab.c:3665
 kmalloc include/linux/slab.h:561 [inline]
 kzalloc include/linux/slab.h:670 [inline]
 vc_do_resize+0x1de/0x12d0 drivers/tty/vt/vt.c:1187
 vc_resize+0x3d/0x60 drivers/tty/vt/vt.c:1304
 vt_ioctl+0x36e/0x21f0 drivers/tty/vt/vt_ioctl.c:840
 tty_ioctl+0x45b/0x12f0 drivers/tty/tty_io.c:2660
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x196/0x1190 fs/ioctl.c:732
 ksys_ioctl+0x62/0x90 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:754
 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10112:
 save_stack+0x21/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:335 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x108/0x2c0 mm/slab.c:3757
 vc_do_resize+0x8a8/0x12d0 drivers/tty/vt/vt.c:1261
 vc_resize+0x3d/0x60 drivers/tty/vt/vt.c:1304
 vt_ioctl+0x36e/0x21f0 drivers/tty/vt/vt_ioctl.c:840
 tty_ioctl+0x45b/0x12f0 drivers/tty/tty_io.c:2660
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x196/0x1190 fs/ioctl.c:732
 ksys_ioctl+0x62/0x90 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:754
 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888099615e40
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 12 bytes inside of
 32-byte region [ffff888099615e40, ffff888099615e60)
The buggy address belongs to the page:
page:ffffea0002658540 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 index:0xffff888099615fc1
raw: 00fffe0000000200 ffffea000278e7c8 ffffea00024f47c8 ffff8880aa4001c0
raw: ffff888099615fc1 ffff888099615000 000000010000003d 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888099615d00: 07 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
 ffff888099615d80: 00 00 01 fc fc fc fc fc fb fb fb fb fc fc fc fc
>ffff888099615e00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                                              ^
 ffff888099615e80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff888099615f00: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc
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