EXT4-fs (loop2): VFS: Can't find ext4 filesystem
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BUG: KASAN: slab-out-of-bounds in soft_cursor+0x95d/0xa40 drivers/video/fbdev/core/softcursor.c:61
Read of size 1 at addr ffff8880a51209a0 by task kworker/1:0/8502

CPU: 1 PID: 8502 Comm: kworker/1:0 Not tainted 4.14.176-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+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 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+0xa9/0x2ae mm/kasan/report.c:393
 soft_cursor+0x95d/0xa40 drivers/video/fbdev/core/softcursor.c:61
 bit_cursor+0x10d9/0x1700 drivers/video/fbdev/core/bitblit.c:386
 fb_flashcursor+0x360/0x400 drivers/video/fbdev/core/fbcon.c:393
 process_one_work+0x813/0x1540 kernel/workqueue.c:2116
 worker_thread+0x5d1/0x1070 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 2300:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15b/0x7c0 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 fbcon_set_font+0x2f8/0x7c0 drivers/video/fbdev/core/fbcon.c:2621
 con_font_set drivers/tty/vt/vt.c:4182 [inline]
 con_font_op+0xb73/0xf70 drivers/tty/vt/vt.c:4247
 vt_ioctl+0x736/0x1f20 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x6c5/0x1220 drivers/tty/tty_io.c:2661
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7

Freed by task 20741:
 save_stack+0x32/0xa0 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+0xcb/0x260 mm/slab.c:3815
 skb_free_head+0x83/0xa0 net/core/skbuff.c:554
 skb_release_data+0x528/0x7b0 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+0xae/0x340 net/core/skbuff.c:663
 macvlan_process_broadcast+0x3b0/0x610 drivers/net/macvlan.c:340
 process_one_work+0x813/0x1540 kernel/workqueue.c:2116
 worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff8880a5120800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 416 bytes inside of
 512-byte region [ffff8880a5120800, ffff8880a5120a00)
The buggy address belongs to the page:
page:ffffea0002944800 count:1 mapcount:0 mapping:ffff8880a5120080 index:0xffff8880a5120300
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a5120080 ffff8880a5120300 0000000100000003
raw: ffffea0002346760 ffffea00027b1620 ffff88812fe56940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a5120880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880a5120900: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a5120980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                               ^
 ffff8880a5120a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a5120a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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