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BUG: KASAN: null-ptr-deref in memmove include/linux/string.h:363 [inline]
BUG: KASAN: null-ptr-deref in scr_memmovew include/linux/vt_buffer.h:68 [inline]
BUG: KASAN: null-ptr-deref in insert_char+0x206/0x450 drivers/tty/vt/vt.c:839
Read of size 18 at addr 0000000000000010 by task syz-executor.3/17094

CPU: 1 PID: 17094 Comm: syz-executor.3 Not tainted 4.19.91-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_error mm/kasan/report.c:352 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x199/0x2ba mm/kasan/report.c:396
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x123/0x190 mm/kasan/kasan.c:267
 memmove+0x24/0x50 mm/kasan/kasan.c:293
 memmove include/linux/string.h:363 [inline]
 scr_memmovew include/linux/vt_buffer.h:68 [inline]
 insert_char+0x206/0x450 drivers/tty/vt/vt.c:839
 csi_at drivers/tty/vt/vt.c:1965 [inline]
 do_con_trol+0x3ca8/0x6070 drivers/tty/vt/vt.c:2412
 do_con_write.part.0+0xfd5/0x1eb0 drivers/tty/vt/vt.c:2773
 do_con_write drivers/tty/vt/vt.c:2541 [inline]
 con_write+0x46/0xd0 drivers/tty/vt/vt.c:3110
 process_output_block drivers/tty/n_tty.c:593 [inline]
 n_tty_write+0x3f9/0x1140 drivers/tty/n_tty.c:2331
 do_tty_write drivers/tty/tty_io.c:960 [inline]
 tty_write+0x458/0x7a0 drivers/tty/tty_io.c:1044
 __vfs_write+0x114/0x810 fs/read_write.c:485
 vfs_write+0x20c/0x560 fs/read_write.c:549
 ksys_write+0x14f/0x2d0 fs/read_write.c:599
 __do_sys_write fs/read_write.c:611 [inline]
 __se_sys_write fs/read_write.c:608 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:608
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a919
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2d2e599c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000000000078 RSI: 0000000020000800 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2d2e59a6d4
R13: 00000000004cbdef R14: 00000000004e5c18 R15: 00000000ffffffff
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