==================================================================
BUG: KASAN: null-ptr-deref in memmove include/linux/string.h:395 [inline]
BUG: KASAN: null-ptr-deref in scr_memmovew include/linux/vt_buffer.h:68 [inline]
BUG: KASAN: null-ptr-deref in insert_char+0x206/0x400 drivers/tty/vt/vt.c:839
Read of size 4294967294 at addr 0000000000000010 by task syz-executor.0/1796

CPU: 1 PID: 1796 Comm: syz-executor.0 Not tainted 5.5.0-rc5-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+0x197/0x210 lib/dump_stack.c:118
 __kasan_report.cold+0x5/0x41 mm/kasan/report.c:510
 kasan_report+0x12/0x20 mm/kasan/common.c:639
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192
 memmove+0x24/0x50 mm/kasan/common.c:116
 memmove include/linux/string.h:395 [inline]
 scr_memmovew include/linux/vt_buffer.h:68 [inline]
 insert_char+0x206/0x400 drivers/tty/vt/vt.c:839
 csi_at drivers/tty/vt/vt.c:1964 [inline]
 do_con_trol+0x41a6/0x61b0 drivers/tty/vt/vt.c:2431
 do_con_write.part.0+0xfd9/0x1ef0 drivers/tty/vt/vt.c:2797
 do_con_write drivers/tty/vt/vt.c:2565 [inline]
 con_write+0x46/0xd0 drivers/tty/vt/vt.c:3135
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x40e/0x1080 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x496/0x7f0 drivers/tty/tty_io.c:1046
 __vfs_write+0x8a/0x110 fs/read_write.c:494
 vfs_write+0x268/0x5d0 fs/read_write.c:558
 ksys_write+0x14f/0x290 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __ia32_sys_write+0x71/0xb0 fs/read_write.c:620
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f3ba39
Code: 00 00 00 89 d3 5b 5e 5f 5d c3 b8 80 96 98 00 eb c4 8b 04 24 c3 8b 1c 24 c3 8b 34 24 c3 8b 3c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5d370cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000000
RDX: 0000000000000078 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
==================================================================