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BUG: KASAN: use-after-free in memcpy include/linux/string.h:347 [inline]
BUG: KASAN: use-after-free in soft_cursor+0x445/0xa40 drivers/video/fbdev/core/softcursor.c:70
Read of size 6 at addr ffff88808b6998ae by task syz-executor.1/32384

CPU: 0 PID: 32384 Comm: syz-executor.1 Not tainted 4.14.181-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1dc 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+0xa9/0x2b9 mm/kasan/report.c:393
 memcpy+0x20/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:347 [inline]
 soft_cursor+0x445/0xa40 drivers/video/fbdev/core/softcursor.c:70
 bit_cursor+0x1072/0x1660 drivers/video/fbdev/core/bitblit.c:386
 fbcon_cursor+0x4b1/0x690 drivers/video/fbdev/core/fbcon.c:1350
 hide_cursor+0x7a/0x2a0 drivers/tty/vt/vt.c:590
 redraw_screen+0x2a2/0x760 drivers/tty/vt/vt.c:680
 vc_do_resize+0xbe0/0xde0 drivers/tty/vt/vt.c:967
 vt_ioctl+0x1a64/0x1f20 drivers/tty/vt/vt_ioctl.c:901
 tty_ioctl+0x6c9/0x1220 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+0x46/0xbb
RIP: 0033:0x45ca29
RSP: 002b:00007fafbf029c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004f2b00 RCX: 000000000045ca29
RDX: 0000000020000000 RSI: 000000000000560a RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000673 R14: 00000000004c9681 R15: 00007fafbf02a6d4

Allocated by task 3638:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x14d/0x3f0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 kernfs_fop_open+0x25d/0xca0 fs/kernfs/file.c:648
 do_dentry_open+0x44b/0xec0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0xb68/0x2aa0 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x292/0x3e0 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 3638:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 kernfs_fop_release+0x10d/0x180 fs/kernfs/file.c:783
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff88808b699800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 174 bytes inside of
 512-byte region [ffff88808b699800, ffff88808b699a00)
The buggy address belongs to the page:
page:ffffea00022da640 count:1 mapcount:0 mapping:ffff88808b699080 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff88808b699080 0000000000000000 0000000100000006
raw: ffffea0002523b60 ffffea00023ef660 ffff8880aa800940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808b699780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808b699800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88808b699880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88808b699900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808b699980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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