==================================================================
BUG: KASAN: slab-out-of-bounds in soft_cursor+0x96a/0xa50 drivers/video/fbdev/core/softcursor.c:61
Read of size 1 at addr ffff88805cb7a410 by task kworker/1:4/9207

CPU: 1 PID: 9207 Comm: kworker/1:4 Not tainted 4.14.209-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+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load1_noabort+0x68/0x70 mm/kasan/report.c:427
 soft_cursor+0x96a/0xa50 drivers/video/fbdev/core/softcursor.c:61
 bit_cursor+0xf7a/0x1580 drivers/video/fbdev/core/bitblit.c:377
 fb_flashcursor+0x356/0x3f0 drivers/video/fbdev/core/fbcon.c:373
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 1847:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 fbcon_set_font+0x2fb/0x7c0 drivers/video/fbdev/core/fbcon.c:2456
 con_font_set drivers/tty/vt/vt.c:4190 [inline]
 con_font_op+0x9e2/0xd90 drivers/tty/vt/vt.c:4234
 vt_ioctl+0xd5d/0x1d50 drivers/tty/vt/vt_ioctl.c:938
 tty_ioctl+0x50f/0x13c0 drivers/tty/tty_io.c:2661
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 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+0x46/0xbb

Freed by task 1221:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 skb_free_head net/core/skbuff.c:554 [inline]
 skb_release_data+0x5f6/0x820 net/core/skbuff.c:574
 skb_release_all net/core/skbuff.c:631 [inline]
 __kfree_skb net/core/skbuff.c:645 [inline]
 consume_skb+0xe0/0x380 net/core/skbuff.c:705
 netlink_broadcast_filtered+0x2ab/0x9e0 net/netlink/af_netlink.c:1489
 kobject_uevent_env+0x9c8/0xf40 lib/kobject_uevent.c:495
 device_del+0x642/0xa80 drivers/base/core.c:2081
 device_unregister+0x22/0xc0 drivers/base/core.c:2103
 bdi_unregister+0x3f9/0x5c0 mm/backing-dev.c:946
 del_gendisk+0x453/0x820 block/genhd.c:726
 loop_remove drivers/block/loop.c:1923 [inline]
 loop_control_ioctl+0x347/0x3f0 drivers/block/loop.c:2021
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 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+0x46/0xbb

The buggy address belongs to the object at ffff88805cb7a300
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 272 bytes inside of
 512-byte region [ffff88805cb7a300, ffff88805cb7a500)
The buggy address belongs to the page:
page:ffffea000172de80 count:1 mapcount:0 mapping:ffff88805cb7a080 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff88805cb7a080 0000000000000000 0000000100000006
raw: ffffea000157da60 ffffea000263d220 ffff88813fe80940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805cb7a300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805cb7a380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805cb7a400: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88805cb7a480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805cb7a500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================