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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 ffff8880a4ccd210 by task kworker/0:5/2274

CPU: 0 PID: 2274 Comm: kworker/0:5 Not tainted 4.19.125-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+0x1fc/0x2fe lib/dump_stack.c:118
 print_address_description.cold+0x54/0x222 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+0x1272/0x1890 drivers/video/fbdev/core/bitblit.c:386
 fb_flashcursor+0x396/0x440 drivers/video/fbdev/core/fbcon.c:399
 process_one_work+0x892/0x1580 kernel/workqueue.c:2155
 worker_thread+0x96/0xe20 kernel/workqueue.c:2298
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 29842:
 __do_kmalloc mm/slab.c:3727 [inline]
 __kmalloc+0x15a/0x3c0 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:4529 [inline]
 con_font_op+0xd3e/0x1130 drivers/tty/vt/vt.c:4594
 vt_ioctl+0xcd0/0x2500 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x7a5/0x1420 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 28775:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xce/0x220 mm/slab.c:3822
 fib6_free_table net/ipv6/ip6_fib.c:249 [inline]
 fib6_net_exit+0x19a/0x2c0 net/ipv6/ip6_fib.c:2225
 ops_exit_list.isra.0+0x9d/0x140 net/core/net_namespace.c:153
 setup_net+0x3db/0x6f0 net/core/net_namespace.c:332
 copy_net_ns+0x1f7/0x332 net/core/net_namespace.c:438
 create_new_namespaces+0x3fb/0x7c0 kernel/nsproxy.c:107
 copy_namespaces+0x325/0x3c0 kernel/nsproxy.c:165
 copy_process.part.0+0x39bf/0x7e80 kernel/fork.c:1900
 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

The buggy address belongs to the object at ffff8880a4ccd000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 16 bytes to the right of
 512-byte region [ffff8880a4ccd000, ffff8880a4ccd200)
The buggy address belongs to the page:
page:ffffea0002933340 count:1 mapcount:0 mapping:ffff88812c3dc940 index:0xffff8880a4ccd780
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea0001456508 ffffea0002331f48 ffff88812c3dc940
raw: ffff8880a4ccd780 ffff8880a4ccd000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a4ccd100: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a4ccd180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a4ccd200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff8880a4ccd280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a4ccd300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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