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BUG: KASAN: slab-out-of-bounds in soft_cursor+0x95a/0xa20 drivers/video/fbdev/core/softcursor.c:61
Read of size 1 at addr ffff888094eef990 by task kworker/0:0/12301

CPU: 0 PID: 12301 Comm: kworker/0:0 Not tainted 4.19.119-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 13971:
 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]
 fbcon_set_font+0x331/0x870 drivers/video/fbdev/core/fbcon.c:2644
 con_font_set drivers/tty/vt/vt.c:4524 [inline]
 con_font_op+0xd3e/0x1130 drivers/tty/vt/vt.c:4589
 vt_ioctl+0xcd0/0x2500 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x7a1/0x1420 drivers/tty/tty_io.c:2669
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcda/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 3698:
 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]
 consume_skb net/core/skbuff.c:705 [inline]
 consume_skb+0xda/0x380 net/core/skbuff.c:699
 skb_free_datagram+0x16/0xf0 net/core/datagram.c:329
 unix_dgram_recvmsg+0x818/0xe10 net/unix/af_unix.c:2203
 sock_recvmsg_nosec net/socket.c:795 [inline]
 sock_recvmsg net/socket.c:802 [inline]
 sock_recvmsg+0xca/0x110 net/socket.c:798
 ___sys_recvmsg+0x271/0x580 net/socket.c:2277
 __sys_recvmsg+0xe9/0x1b0 net/socket.c:2326
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888094eef800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
 512-byte region [ffff888094eef800, ffff888094eefa00)
The buggy address belongs to the page:
page:ffffea000253bbc0 count:1 mapcount:0 mapping:ffff88812c39c940 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea0002824d08 ffffea000281a7c8 ffff88812c39c940
raw: 0000000000000000 ffff888094eef080 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888094eef880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888094eef900: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888094eef980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff888094eefa00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888094eefa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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