richedit: Fixed Valgrind error related to undoing.

The error was a memory access of a freed object. In ME_AddUndoItem I checked the top of the undo stack to end a coalescing undo transaction, assuming that this should be either a valid undo item, or NULL, instead it was already freed.

richedit: Fixed Valgrind error related to undoing.
ebded163 · Dylan Smith · Alexandre Julliard · 5b2bdc06 · ebded163
Commit ebded163 authored Jul 06, 2008 by Dylan Smith Committed by Alexandre Julliard Jul 07, 2008
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Showing with 19 additions and 18 deletions

undo.c dlls/riched20/undo.c +19 -18

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--- a/dlls/riched20/undo.c
+++ b/dlls/riched20/undo.c
@@ -55,13 +55,7 @@ ME_UndoItem *ME_AddUndoItem(ME_TextEditor *editor, ME_DIType type, const ME_Disp
    return NULL;
  else
  {
-    ME_DisplayItem *pItem;
-    if (editor->pUndoStack
-        && editor->pUndoStack->type == diUndoPotentialEndTransaction)
-    {
-        editor->pUndoStack->type = diUndoEndTransaction;
-    }
-    pItem = (ME_DisplayItem *)ALLOC_OBJ(ME_UndoItem);
+    ME_DisplayItem *pItem = (ME_DisplayItem *)ALLOC_OBJ(ME_UndoItem);
    ((ME_UndoItem *)pItem)->nCR = ((ME_UndoItem *)pItem)->nLF = -1;
    switch(type)
    {
@@ -109,6 +103,11 @@ ME_UndoItem *ME_AddUndoItem(ME_TextEditor *editor, ME_DIType type, const ME_Disp
    pItem->prev = NULL;
    if (editor->nUndoMode == umAddToUndo || editor->nUndoMode == umAddBackToUndo)
    {
+      if (editor->pUndoStack
+          && editor->pUndoStack->type == diUndoPotentialEndTransaction)
+      {
+          editor->pUndoStack->type = diUndoEndTransaction;
+      }
      if (editor->nUndoMode == umAddToUndo)
        TRACE("Pushing id=%s to undo stack, deleting redo stack\n", ME_GetDITypeName(type));
      else
@@ -355,17 +354,18 @@ BOOL ME_Undo(ME_TextEditor *editor) {
  editor->nUndoMode = umAddToRedo;
  p = editor->pUndoStack->next;
  ME_DestroyDisplayItem(editor->pUndoStack);
+  editor->pUndoStack = p;
  do {
-    ME_DisplayItem *pp = p;
+    p->prev = NULL;
    ME_PlayUndoItem(editor, p);
-    p = p->next;
-    ME_DestroyDisplayItem(pp);
+    editor->pUndoStack = p->next;
+    ME_DestroyDisplayItem(p);
+    p = editor->pUndoStack;
  } while(p && p->type != diUndoEndTransaction);
-  ME_AddUndoItem(editor, diUndoEndTransaction, NULL);
-  editor->pUndoStack = p;
-  editor->nUndoStackSize--;
  if (p)
    p->prev = NULL;
+  ME_AddUndoItem(editor, diUndoEndTransaction, NULL);
+  editor->nUndoStackSize--;
  editor->nUndoMode = nMode;
  ME_UpdateRepaint(editor);
  return TRUE;
@@ -389,16 +389,17 @@ BOOL ME_Redo(ME_TextEditor *editor) {
  editor->nUndoMode = umAddBackToUndo;
  p = editor->pRedoStack->next;
  ME_DestroyDisplayItem(editor->pRedoStack);
+  editor->pRedoStack = p;
  do {
-    ME_DisplayItem *pp = p;
+    p->prev = NULL;
    ME_PlayUndoItem(editor, p);
-    p = p->next;
-    ME_DestroyDisplayItem(pp);
+    editor->pRedoStack = p->next;
+    ME_DestroyDisplayItem(p);
+    p = editor->pRedoStack;
  } while(p && p->type != diUndoEndTransaction);
-  ME_AddUndoItem(editor, diUndoEndTransaction, NULL);
-  editor->pRedoStack = p;
  if (p)
    p->prev = NULL;
+  ME_AddUndoItem(editor, diUndoEndTransaction, NULL);
  editor->nUndoMode = nMode;
  ME_UpdateRepaint(editor);
  return TRUE;