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BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:347 [inline]
BUG: KASAN: slab-out-of-bounds in soft_cursor+0x445/0xa40 drivers/video/fbdev/core/softcursor.c:70
Read of size 3 at addr ffff8880a17a64ad by task kworker/0:3/7587

CPU: 0 PID: 7587 Comm: kworker/0:3 Not tainted 4.14.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient fb_flashcursor
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393
 memcpy+0x20/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:347 [inline]
 soft_cursor+0x445/0xa40 drivers/video/fbdev/core/softcursor.c:70
 bit_cursor+0x10d9/0x1700 drivers/video/fbdev/core/bitblit.c:386
 fb_flashcursor+0x360/0x400 drivers/video/fbdev/core/fbcon.c:393
 process_one_work+0x813/0x1540 kernel/workqueue.c:2114
 worker_thread+0x5d1/0x1070 kernel/workqueue.c:2248
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 9140:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15b/0x7c0 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 fbcon_set_font+0x2f8/0x7c0 drivers/video/fbdev/core/fbcon.c:2618
 con_font_set drivers/tty/vt/vt.c:4162 [inline]
 con_font_op+0xb73/0xf70 drivers/tty/vt/vt.c:4227
 vt_ioctl+0xaf8/0x1f00 drivers/tty/vt/vt_ioctl.c:918
 tty_ioctl+0x6c5/0x1220 drivers/tty/tty_io.c:2661
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 7524:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 kernfs_fop_release+0x10d/0x180 fs/kernfs/file.c:783
 __fput+0x25f/0x790 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1d6/0x220 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8880a17a62c0
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 493 bytes inside of
 512-byte region [ffff8880a17a62c0, ffff8880a17a64c0)
The buggy address belongs to the page:
page:ffffea000285e980 count:1 mapcount:0 mapping:ffff8880a17a6040 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a17a6040 0000000000000000 0000000100000006
raw: ffffea0001dcdf20 ffffea000223e920 ffff88812fe56940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a17a6380: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff8880a17a6400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a17a6480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                  ^
 ffff8880a17a6500: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8880a17a6580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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