From 338f1fc0ee3ca929387448fe464579d6113fa76a Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Thu, 26 May 2022 15:56:23 +0100
Subject: [PATCH] patch 8.2.5023: substitute overwrites allocated buffer

Problem:    Substitute overwrites allocated buffer.
Solution:   Disallow undo when in a substitute command.
---
 src/normal.c                    | 42 ++++++++++++++++-----------------
 src/testdir/test_substitute.vim | 22 +++++++++++++++++
 src/undo.c                      |  6 +++++
 src/version.c                   |  2 ++
 4 files changed, 51 insertions(+), 21 deletions(-)

--- a/src/normal.c
+++ b/src/normal.c
@@ -515,6 +515,22 @@ find_command(int cmdchar)
 }
 
 /*
+ * If currently editing a cmdline or text is locked: beep and give an error
+ * message, return TRUE.
+ */
+    static int
+check_text_locked(oparg_T *oap)
+{
+    if (text_locked())
+    {
+	clearopbeep(oap);
+	text_locked_msg();
+	return TRUE;
+    }
+    return FALSE;
+}
+
+/*
  * Execute a command in Normal mode.
  */
     void
@@ -775,14 +791,9 @@ getcount:
 	goto normal_end;
     }
 
-    if (text_locked() && (nv_cmds[idx].cmd_flags & NV_NCW))
-    {
-	/* This command is not allowed while editing a cmdline: beep. */
-	clearopbeep(oap);
-	text_locked_msg();
-	goto normal_end;
-    }
-    if ((nv_cmds[idx].cmd_flags & NV_NCW) && curbuf_locked())
+    if ((nv_cmds[idx].cmd_flags & NV_NCW)
+				&& (check_text_locked(oap) || curbuf_locked()))
+	/* this command is not allowed now */
 	goto normal_end;
 
     /*
@@ -6162,12 +6173,8 @@ nv_gotofile(cmdarg_T *cap)
     char_u	*ptr;
     linenr_T	lnum = -1;
 
-    if (text_locked())
-    {
-	clearopbeep(cap->oap);
-	text_locked_msg();
+    if (check_text_locked(cap->oap))
 	return;
-    }
     if (curbuf_locked())
     {
 	clearop(cap->oap);
@@ -8328,14 +8335,7 @@ nv_g_cmd(cmdarg_T *cap)
 
     /* "gQ": improved Ex mode */
     case 'Q':
-	if (text_locked())
-	{
-	    clearopbeep(cap->oap);
-	    text_locked_msg();
-	    break;
-	}
-
-	if (!checkclearopq(oap))
+	if (!check_text_locked(cap->oap) && !checkclearopq(oap))
 	    do_exmode(TRUE);
 	break;
 
--- a/src/testdir/test_substitute.vim
+++ b/src/testdir/test_substitute.vim
@@ -530,3 +530,25 @@ func Test_sub_change_window()
   delfunc Repl
 endfunc
 
+" This was undoign a change in between computing the length and using it.
+func Do_Test_sub_undo_change()
+  new
+  norm o0000000000000000000000000000000000000000000000000000
+  silent! s/\%')/\=Repl()
+  bwipe!
+endfunc
+
+func Test_sub_undo_change()
+  func Repl()
+    silent! norm g-
+  endfunc
+  call Do_Test_sub_undo_change()
+
+  func! Repl()
+    silent earlier
+  endfunc
+  call Do_Test_sub_undo_change()
+
+  delfunc Repl
+endfunc
+
--- a/src/undo.c
+++ b/src/undo.c
@@ -2278,6 +2278,12 @@ undo_time(
     int		    above = FALSE;
     int		    did_undo = TRUE;
 
+    if (text_locked())
+    {
+	text_locked_msg();
+	return;
+    }
+
     /* First make sure the current undoable change is synced. */
     if (curbuf->b_u_synced == FALSE)
 	u_sync(TRUE);
--- a/src/version.c
+++ b/src/version.c
@@ -796,6 +796,8 @@ static int included_patches[] =
 /**/
     5024,
 /**/
+    5023,
+/**/
     4977,
 /**/
     4921,