From c249913edc35c0e666d783bfc21595cf9f7d9e0d Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Fri, 16 Sep 2022 22:16:59 +0100
Subject: [PATCH] patch 9.0.0483: illegal memory access when replacing in
 virtualedit mode

Problem:    Illegal memory access when replacing in virtualedit mode.
Solution:   Check for replacing NUL after Tab.
---
 src/ops.c                        | 12 ++++++++++--
 src/testdir/test_virtualedit.vim | 14 ++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/ops.c b/src/ops.c
index b930878..33cbd8e 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -1160,6 +1160,8 @@ op_replace(oparg_T *oap, int c)
 
 	while (LTOREQ_POS(curwin->w_cursor, oap->end))
 	{
+	    int done = FALSE;
+
 	    n = gchar_cursor();
 	    if (n != NUL)
 	    {
@@ -1173,6 +1175,7 @@ op_replace(oparg_T *oap, int c)
 		    if (curwin->w_cursor.lnum == oap->end.lnum)
 			oap->end.col += new_byte_len - old_byte_len;
 		    replace_character(c);
+		    done = TRUE;
 		}
 		else
 		{
@@ -1191,10 +1194,15 @@ op_replace(oparg_T *oap, int c)
 			if (curwin->w_cursor.lnum == oap->end.lnum)
 			    getvpos(&oap->end, end_vcol);
 		    }
-		    PBYTE(curwin->w_cursor, c);
+		    // with "coladd" set may move to just after a TAB
+		    if (gchar_cursor() != NUL)
+		    {
+			PBYTE(curwin->w_cursor, c);
+			done = TRUE;
+		    }
 		}
 	    }
-	    else if (virtual_op && curwin->w_cursor.lnum == oap->end.lnum)
+	    if (!done && virtual_op && curwin->w_cursor.lnum == oap->end.lnum)
 	    {
 		int virtcols = oap->end.coladd;
 
diff --git a/src/testdir/test_virtualedit.vim b/src/testdir/test_virtualedit.vim
index b31f3a2..0031b22 100644
--- a/src/testdir/test_virtualedit.vim
+++ b/src/testdir/test_virtualedit.vim
@@ -537,4 +537,18 @@ func Test_global_local_virtualedit()
   set virtualedit&
 endfunc
 
+" this was replacing the NUL at the end of the line 
+func Test_virtualedit_replace_after_tab()
+  new
+  s/\v/	0
+  set ve=all
+  let @" = ''
+  sil! norm vPvr0
+  
+  call assert_equal("\t0", getline(1))
+  set ve&
+  bwipe!
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab
-- 
2.27.0