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BUG: KASAN: slab-out-of-bounds in soft_cursor+0x3fe/0xdb0 drivers/video/fbdev/core/softcursor.c:70
Read of size 8 at addr ffff888064f1e510 by task syz-executor.1/26130

CPU: 0 PID: 26130 Comm: syz-executor.1 Not tainted 5.8.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1f0/0x31e lib/dump_stack.c:118
 print_address_description+0x66/0x5a0 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report+0x132/0x1d0 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:183 [inline]
 check_memory_region+0x2b5/0x2f0 mm/kasan/generic.c:192
 memcpy+0x25/0x60 mm/kasan/common.c:105
 soft_cursor+0x3fe/0xdb0 drivers/video/fbdev/core/softcursor.c:70
 bit_cursor+0x178a/0x2180 drivers/video/fbdev/core/bitblit.c:386
 hide_cursor+0x7e/0x310 drivers/tty/vt/vt.c:902
 do_con_write+0x17e/0xf2d0 drivers/tty/vt/vt.c:2617
 con_write+0x20/0x40 drivers/tty/vt/vt.c:3159
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0xcbf/0x1170 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x593/0x940 drivers/tty/tty_io.c:1046
 vfs_write+0x2dd/0xc70 fs/read_write.c:576
 ksys_write+0x11b/0x220 fs/read_write.c:631
 do_syscall_64+0x73/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1f9
Code: Bad RIP value.
RSP: 002b:00007f8939e65c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000036dc0 RCX: 000000000045c1f9
RDX: 0000000000001006 RSI: 0000000020001440 RDI: 0000000000000008
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffc21e3e97f R14: 00007f8939e669c0 R15: 000000000078bf0c

Allocated by task 7031:
 save_stack mm/kasan/common.c:48 [inline]
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc+0x103/0x140 mm/kasan/common.c:494
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x24b/0x330 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 fbcon_set_font+0x2c4/0x970 drivers/video/fbdev/core/fbcon.c:2673
 con_font_set drivers/tty/vt/vt.c:4571 [inline]
 con_font_op+0xebc/0x1630 drivers/tty/vt/vt.c:4636
 vt_ioctl+0x179d/0x3ec0 drivers/tty/vt/vt_ioctl.c:265
 tty_ioctl+0xee4/0x15c0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl fs/ioctl.c:753 [inline]
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:760
 do_syscall_64+0x73/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6626:
 save_stack mm/kasan/common.c:48 [inline]
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0x114/0x170 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 skb_release_all net/core/skbuff.c:664 [inline]
 __kfree_skb+0x56/0x1c0 net/core/skbuff.c:678
 netlink_broadcast_filtered+0x1035/0x1150 net/netlink/af_netlink.c:1513
 netlink_broadcast+0x35/0x50 net/netlink/af_netlink.c:1535
 rtnetlink_send+0x112/0x170 net/core/rtnetlink.c:714
 tc_chain_notify_delete net/sched/cls_api.c:2745 [inline]
 __tcf_chain_put+0x25a/0x730 net/sched/cls_api.c:565
 tcf_chain_put net/sched/cls_api.c:583 [inline]
 tc_new_tfilter+0xf3a/0x2df0 net/sched/cls_api.c:2147
 rtnetlink_rcv_msg+0x8fb/0xd40 net/core/rtnetlink.c:5451
 netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2469
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x519/0x800 net/socket.c:2352
 ___sys_sendmsg net/socket.c:2406 [inline]
 __sys_sendmmsg+0x45b/0x680 net/socket.c:2496
 __do_sys_sendmmsg net/socket.c:2525 [inline]
 __se_sys_sendmmsg net/socket.c:2522 [inline]
 __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2522
 do_syscall_64+0x73/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888064f1e400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 272 bytes inside of
 512-byte region [ffff888064f1e400, ffff888064f1e600)
The buggy address belongs to the page:
page:ffffea000193c780 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00018f9548 ffffea0001916748 ffff8880aa400a80
raw: 0000000000000000 ffff888064f1e000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888064f1e400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888064f1e480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888064f1e500: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff888064f1e580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888064f1e600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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