From c99cbf8f289bdda5d4a77d7ec415850a520330ba Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Sat, 4 Mar 2023 14:13:10 +0000
Subject: [PATCH] patch 9.0.1378: illegal memory access when using virtual
 editing

Problem:    Illegal memory access when using virtual editing.
Solution:   Make sure "startspaces" is not negative.
---
 src/register.c                   |  2 ++
 src/testdir/test_virtualedit.vim | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/src/register.c b/src/register.c
index 461363be378d..f3df79cfd642 100644
--- a/src/register.c
+++ b/src/register.c
@@ -1247,6 +1247,8 @@ op_yank(oparg_T *oap, int deleting, int mess)
 				// double-count it.
 				bd.startspaces = (ce - cs + 1)
 							  - oap->start.coladd;
+				if (bd.startspaces < 0)
+				    bd.startspaces = 0;
 				startcol++;
 			    }
 			}
diff --git a/src/testdir/test_virtualedit.vim b/src/testdir/test_virtualedit.vim
index 71cea427bac1..edaae678609d 100644
--- a/src/testdir/test_virtualedit.vim
+++ b/src/testdir/test_virtualedit.vim
@@ -88,6 +88,16 @@ func Test_edit_change()
   set virtualedit=
 endfunc
 
+func Test_edit_special_char()
+  new
+  se ve=all
+  norm a0
+  sil! exe "norm o00000\<Nul>k<a0s"
+
+  bwipe!
+  set virtualedit=
+endfunc
+
 " Tests for pasting at the beginning, end and middle of a tab character
 " in virtual edit mode.
 func Test_paste_in_tab()