==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:347 [inline]
BUG: KASAN: slab-out-of-bounds in soft_cursor+0x43d/0xa50 drivers/video/fbdev/core/softcursor.c:70
Read of size 8 at addr ffff88805dacb910 by task kworker/1:0/18

CPU: 1 PID: 18 Comm: kworker/1:0 Not tainted 4.14.165-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
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x123/0x190 mm/kasan/kasan.c:267
 memcpy+0x24/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:347 [inline]
 soft_cursor+0x43d/0xa50 drivers/video/fbdev/core/softcursor.c:70
 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 27215:
 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 3719:
 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_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcc/0x270 mm/slab.c:3815
 skb_free_head+0x8b/0xb0 net/core/skbuff.c:554
 skb_release_data+0x543/0x7c0 net/core/skbuff.c:574
 skb_release_all+0x4d/0x60 net/core/skbuff.c:631
 __kfree_skb net/core/skbuff.c:645 [inline]
 consume_skb+0xaf/0x340 net/core/skbuff.c:705
 netlink_broadcast_filtered+0x2ae/0x9e0 net/netlink/af_netlink.c:1488
 kobject_uevent_env+0x85a/0xc80 lib/kobject_uevent.c:495
 kobject_synth_uevent+0x5e3/0x6fa lib/kobject_uevent.c:205
 uevent_store+0x26/0x70 drivers/base/core.c:997
 dev_attr_store+0x59/0x80 drivers/base/core.c:715
 sysfs_kf_write+0x10c/0x160 fs/sysfs/file.c:141
 kernfs_fop_write+0x291/0x450 fs/kernfs/file.c:316
 __vfs_write+0x105/0x6b0 fs/read_write.c:480
 vfs_write+0x198/0x500 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xfd/0x230 fs/read_write.c:582
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88805dacb800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 272 bytes inside of
 512-byte region [ffff88805dacb800, ffff88805dacba00)
The buggy address belongs to the page:
page:ffffea000176b2c0 count:1 mapcount:0 mapping:ffff88805dacb080 index:0xffff88805dacb300
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff88805dacb080 ffff88805dacb300 0000000100000002
raw: ffffea0002511ca0 ffffea000294d0a0 ffff8880aa800940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805dacb800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805dacb880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805dacb900: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88805dacb980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805dacba00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================