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BUG: KASAN: slab-out-of-bounds in soft_cursor+0x96b/0xa30 drivers/video/fbdev/core/softcursor.c:61
Read of size 1 at addr ffff88809383a598 by task kworker/1:1/20147

CPU: 1 PID: 20147 Comm: kworker/1:1 Not tainted 5.8.0-rc5-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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 soft_cursor+0x96b/0xa30 drivers/video/fbdev/core/softcursor.c:61
 bit_cursor+0x1166/0x17d0 drivers/video/fbdev/core/bitblit.c:386
 fb_flashcursor+0x371/0x3e0 drivers/video/fbdev/core/fbcon.c:417
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Allocated by task 13303:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x17a/0x340 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 fbcon_set_font+0x34f/0x8b0 drivers/video/fbdev/core/fbcon.c:2673
 con_font_set drivers/tty/vt/vt.c:4571 [inline]
 con_font_op+0xd25/0x1110 drivers/tty/vt/vt.c:4636
 vt_ioctl+0x1180/0x2670 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 3880:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 skb_free_head net/core/skbuff.c:590 [inline]
 skb_release_data+0x6d9/0x910 net/core/skbuff.c:610
 skb_release_all net/core/skbuff.c:664 [inline]
 __kfree_skb net/core/skbuff.c:678 [inline]
 consume_skb net/core/skbuff.c:837 [inline]
 consume_skb+0xc2/0x160 net/core/skbuff.c:831
 skb_free_datagram+0x16/0xf0 net/core/datagram.c:325
 unix_dgram_recvmsg+0x6ee/0xb60 net/unix/af_unix.c:2188
 sock_recvmsg_nosec net/socket.c:886 [inline]
 sock_recvmsg net/socket.c:904 [inline]
 sock_recvmsg net/socket.c:900 [inline]
 ____sys_recvmsg+0x2c4/0x640 net/socket.c:2575
 ___sys_recvmsg+0x127/0x200 net/socket.c:2617
 __sys_recvmsg+0xe2/0x1a0 net/socket.c:2651
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88809383a400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 408 bytes inside of
 512-byte region [ffff88809383a400, ffff88809383a600)
The buggy address belongs to the page:
page:ffffea00024e0e80 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88809383a000
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002885248 ffffea00029f6e88 ffff8880aa000a80
raw: ffff88809383a000 ffff88809383a000 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809383a480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88809383a500: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809383a580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                            ^
 ffff88809383a600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809383a680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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