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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 ffff88809d7f2db0 by task kworker/0:1/3069

CPU: 0 PID: 3069 Comm: kworker/0:1 Not tainted 4.19.135-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+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load1_noabort+0x88/0x90 mm/kasan/report.c:430
 soft_cursor+0x96b/0xa30 drivers/video/fbdev/core/softcursor.c:61
 bit_cursor+0x1239/0x1820 drivers/video/fbdev/core/bitblit.c:386
 fb_flashcursor+0x397/0x440 drivers/video/fbdev/core/fbcon.c:399
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 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 10550:
 __do_kmalloc mm/slab.c:3727 [inline]
 __kmalloc+0x15a/0x3c0 mm/slab.c:3736
 kmalloc include/linux/slab.h:520 [inline]
 fbcon_set_font+0x34f/0x8a0 drivers/video/fbdev/core/fbcon.c:2644
 con_font_set drivers/tty/vt/vt.c:4536 [inline]
 con_font_op+0xd02/0x10e0 drivers/tty/vt/vt.c:4601
 vt_ioctl+0x116d/0x24d0 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x5b0/0x15c0 drivers/tty/tty_io.c:2669
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcdb/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 3711:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x210 mm/slab.c:3822
 skb_free_head net/core/skbuff.c:554 [inline]
 skb_release_data+0x6de/0x920 net/core/skbuff.c:574
 skb_release_all net/core/skbuff.c:631 [inline]
 __kfree_skb net/core/skbuff.c:645 [inline]
 consume_skb+0x113/0x3d0 net/core/skbuff.c:705
 skb_free_datagram+0x16/0xf0 net/core/datagram.c:329
 unix_dgram_recvmsg+0x73e/0xe80 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+0x255/0x570 net/socket.c:2277
 __sys_recvmsg net/socket.c:2326 [inline]
 __do_sys_recvmsg net/socket.c:2336 [inline]
 __se_sys_recvmsg net/socket.c:2333 [inline]
 __x64_sys_recvmsg+0x12f/0x220 net/socket.c:2333
 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 ffff88809d7f2c80
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 304 bytes inside of
 512-byte region [ffff88809d7f2c80, ffff88809d7f2e80)
The buggy address belongs to the page:
page:ffffea000275fc80 count:1 mapcount:0 mapping:ffff88812c39c940 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea0002321d08 ffffea00027f9048 ffff88812c39c940
raw: 0000000000000000 ffff88809d7f2000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809d7f2c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88809d7f2d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88809d7f2d80: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffff88809d7f2e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809d7f2e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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