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BUG: KASAN: slab-out-of-bounds in soft_cursor+0x97a/0xa50 drivers/video/fbdev/core/softcursor.c:61
Read of size 1 at addr ffff8880a12b7278 by task kworker/0:3/2875

CPU: 0 PID: 2875 Comm: kworker/0:3 Not tainted 4.14.164-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+0x142/0x197 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1dc 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+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:427
 soft_cursor+0x97a/0xa50 drivers/video/fbdev/core/softcursor.c:61
 bit_cursor+0x11be/0x1830 drivers/video/fbdev/core/bitblit.c:386
 fb_flashcursor+0x36d/0x410 drivers/video/fbdev/core/fbcon.c:393
 process_one_work+0x863/0x1600 kernel/workqueue.c:2114
 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 7729:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15d/0x7a0 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 fbcon_set_font+0x2f8/0x7b0 drivers/video/fbdev/core/fbcon.c:2618
 con_font_set drivers/tty/vt/vt.c:4162 [inline]
 con_font_op+0xc0f/0x1060 drivers/tty/vt/vt.c:4227
 vt_ioctl+0xb80/0x2170 drivers/tty/vt/vt_ioctl.c:927
 tty_ioctl+0x841/0x1320 drivers/tty/tty_io.c:2661
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880a12b7040
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 56 bytes to the right of
 512-byte region [ffff8880a12b7040, ffff8880a12b7240)
The buggy address belongs to the page:
page:ffffea000284adc0 count:1 mapcount:0 mapping:ffff8880a12b7040 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a12b7040 0000000000000000 0000000100000006
raw: ffffea000236a960 ffffea00015b98a0 ffff8880aa800940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a12b7100: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff8880a12b7180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a12b7200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                                ^
 ffff8880a12b7280: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff8880a12b7300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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