==================================================================
BUG: KASAN: slab-out-of-bounds in soft_cursor+0x95a/0xa20 drivers/video/fbdev/core/softcursor.c:61
Read of size 1 at addr ffff88808afb3c10 by task kworker/0:3/18206

CPU: 0 PID: 18206 Comm: kworker/0:3 Not tainted 4.19.115-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:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.cold+0x7c/0x212 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x88/0x2b9 mm/kasan/report.c:396
 soft_cursor+0x95a/0xa20 drivers/video/fbdev/core/softcursor.c:61
 bit_cursor+0x1230/0x1900 drivers/video/fbdev/core/bitblit.c:386
 fb_flashcursor+0x396/0x440 drivers/video/fbdev/core/fbcon.c:399
 process_one_work+0x91f/0x1640 kernel/workqueue.c:2155
 worker_thread+0x96/0xe20 kernel/workqueue.c:2298
 kthread+0x34a/0x420 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 1610:
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:531
 __do_kmalloc mm/slab.c:3727 [inline]
 __kmalloc+0x15b/0x770 mm/slab.c:3736
 kmalloc include/linux/slab.h:520 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 __register_sysctl_table+0xc3/0xef0 fs/proc/proc_sysctl.c:1310
 setup_userns_sysctls+0xbf/0x180 kernel/ucount.c:98
 create_user_ns+0x59f/0x9d0 kernel/user_namespace.c:140
 copy_creds+0x4a4/0x5f0 kernel/cred.c:353
 copy_process.part.0+0xb78/0x7a60 kernel/fork.c:1770
 copy_process kernel/fork.c:1694 [inline]
 _do_fork+0x22f/0xf40 kernel/fork.c:2207
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 18:
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/kasan.c:521
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xce/0x220 mm/slab.c:3822
 skb_free_head+0x91/0xb0 net/core/skbuff.c:554
 skb_release_data+0x600/0x8c0 net/core/skbuff.c:574
 skb_release_all+0x46/0x60 net/core/skbuff.c:631
 __kfree_skb net/core/skbuff.c:645 [inline]
 kfree_skb net/core/skbuff.c:663 [inline]
 kfree_skb+0xe1/0x390 net/core/skbuff.c:657
 __netif_receive_skb_core+0x54a/0x2e80 net/core/dev.c:4930
 __netif_receive_skb_one_core+0x99/0x160 net/core/dev.c:4947
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5061
 process_backlog+0x233/0x7c0 net/core/dev.c:5843
 napi_poll net/core/dev.c:6266 [inline]
 net_rx_action+0x4ab/0xfc0 net/core/dev.c:6332
 __do_softirq+0x26c/0x93c kernel/softirq.c:292

The buggy address belongs to the object at ffff88808afb3a80
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
 512-byte region [ffff88808afb3a80, ffff88808afb3c80)
The buggy address belongs to the page:
page:ffffea00022becc0 count:1 mapcount:0 mapping:ffff88812c3dc940 index:0xffff88808afb3580
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea00027fc988 ffffea0002658948 ffff88812c3dc940
raw: ffff88808afb3580 ffff88808afb3080 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808afb3b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88808afb3b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
>ffff88808afb3c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88808afb3c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808afb3d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================