sp0: Synchronizing with TNC
==================================================================
BUG: KASAN: use-after-free in fbcon_cursor+0x59d/0x690 drivers/video/fbdev/core/fbcon.c:1325
Read of size 2 at addr ffff88804135321e by task syz-executor.4/28944

CPU: 0 PID: 28944 Comm: syz-executor.4 Not tainted 4.14.175-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+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 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+0xa9/0x2ae mm/kasan/report.c:393
 fbcon_cursor+0x59d/0x690 drivers/video/fbdev/core/fbcon.c:1325
 fbcon_scrolldelta+0x57f/0x10c0 drivers/video/fbdev/core/fbcon.c:2832
 fbcon_set_origin+0x32/0x40 drivers/video/fbdev/core/fbcon.c:2883
 set_origin+0x2cc/0x3b0 drivers/tty/vt/vt.c:614
 vc_do_resize+0x5e7/0xde0 drivers/tty/vt/vt.c:947
 vt_ioctl+0xe14/0x1f20 drivers/tty/vt/vt_ioctl.c:850
 tty_ioctl+0x6c5/0x1220 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+0x42/0xb7
RIP: 0033:0x45c889
RSP: 002b:00007fa2e8172c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa2e81736d4 RCX: 000000000045c889
RDX: 0000000020000080 RSI: 0000000000005609 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000669 R14: 00000000004c9416 R15: 000000000076bf0c

Allocated by task 22742:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15b/0x7c0 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 vc_do_resize+0x1c1/0xde0 drivers/tty/vt/vt.c:885
 vt_ioctl+0xe14/0x1f20 drivers/tty/vt/vt_ioctl.c:850
 tty_ioctl+0x6c5/0x1220 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+0x42/0xb7

Freed by task 28944:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 vc_do_resize+0x58b/0xde0 drivers/tty/vt/vt.c:944
 vt_ioctl+0xe14/0x1f20 drivers/tty/vt/vt_ioctl.c:850
 tty_ioctl+0x6c5/0x1220 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+0x42/0xb7

The buggy address belongs to the object at ffff888041353040
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 478 bytes inside of
 512-byte region [ffff888041353040, ffff888041353240)
The buggy address belongs to the page:
page:ffffea000104d4c0 count:1 mapcount:0 mapping:ffff888041353040 index:0xffff888041353cc0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff888041353040 ffff888041353cc0 0000000100000002
raw: ffffea00011dfe20 ffffea00023464e0 ffff88812fe56940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888041353100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888041353180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888041353200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                            ^
 ffff888041353280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff888041353300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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