sw: fix wrong downcast in UndoManager::IsViewUndoActionIndependent()

In case a user types in one view, an other user types in an other view,
finally the first user deletes, then getting the undo state resulted in
a memory corruption.

This went wrong in commit 2875c65946e59f5dd7968155463bf00bd71d440b (sw,
out of order undo: allow a subset of a non-empty redo list, 2021-11-11),
the intention was to check if we have a redo item and it has the
expected type, but we checked the type of an earlier undo action that
belongs to the view.

Fix the problem by checking the type of the correct undo action, this
was probably a copy&paste error of mine.

Resolves <https://github.com/CollaboraOnline/online/issues/6412>.

Change-Id: I6cb2a081067695a045d86b4ef427cc5a76c0f9c4
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/152204
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>

2 files changed, 43 insertions, 1 deletions

diff --git a/sw/qa/extras/tiledrendering/tiledrendering.cxx b/sw/qa/extras/tiledrendering/tiledrendering.cxx
index 2fbe09c0a90b..a0345e712714 100644
--- a/sw/qa/extras/tiledrendering/tiledrendering.cxx
+++ b/sw/qa/extras/tiledrendering/tiledrendering.cxx
@@ -1300,6 +1300,48 @@ CPPUNIT_TEST_FIXTURE(SwTiledRenderingTest, testUndoReorderingRedo)
     SfxViewShell::Current()->setLibreOfficeKitViewCallback(nullptr);
 }
 
+CPPUNIT_TEST_FIXTURE(SwTiledRenderingTest, testUndoReorderingRedo2)
+{
+    // Create two views.
+    SwXTextDocument* pXTextDocument = createDoc();
+    SwWrtShell* pWrtShell1 = pXTextDocument->GetDocShell()->GetWrtShell();
+    int nView1 = SfxLokHelper::getView();
+    int nView2 = SfxLokHelper::createView();
+    pXTextDocument->initializeForTiledRendering(uno::Sequence<beans::PropertyValue>());
+    SwWrtShell* pWrtShell2 = pXTextDocument->GetDocShell()->GetWrtShell();
+
+    // Type in the first view.
+    SfxLokHelper::setView(nView1);
+    pWrtShell1->SttEndDoc(/*bStt=*/true);
+    pXTextDocument->postKeyEvent(LOK_KEYEVENT_KEYINPUT, 'f', 0);
+    pXTextDocument->postKeyEvent(LOK_KEYEVENT_KEYUP, 'f', 0);
+    Scheduler::ProcessEventsToIdle();
+
+    // Type to the same paragraph in the second view.
+    SfxLokHelper::setView(nView2);
+    pWrtShell2->SttEndDoc(/*bStt=*/true);
+    pXTextDocument->postKeyEvent(LOK_KEYEVENT_KEYINPUT, 's', 0);
+    pXTextDocument->postKeyEvent(LOK_KEYEVENT_KEYUP, 's', 0);
+    Scheduler::ProcessEventsToIdle();
+
+    // Delete in the first view and undo.
+    SfxLokHelper::setView(nView1);
+    pXTextDocument->postKeyEvent(LOK_KEYEVENT_KEYINPUT, 0, awt::Key::BACKSPACE);
+    pXTextDocument->postKeyEvent(LOK_KEYEVENT_KEYUP, 0, awt::Key::BACKSPACE);
+    Scheduler::ProcessEventsToIdle();
+    dispatchCommand(mxComponent, ".uno:Undo", {});
+    Scheduler::ProcessEventsToIdle();
+
+    // Query the undo state, now that a "delete" is on the redo stack and an "insert" belongs to the
+    // view on the undo stack, so the types are different.
+    SwUndoId nUndoId(SwUndoId::EMPTY);
+    // Without the accompanying fix in place, this test would have failed with:
+    // runtime error: downcast which does not point to an object of type 'const SwUndoInsert'
+    // note: object is of type 'SwUndoDelete'
+    // in an UBSan build.
+    pWrtShell1->GetLastUndoInfo(nullptr, &nUndoId, &pWrtShell1->GetView());
+}
+
 CPPUNIT_TEST_FIXTURE(SwTiledRenderingTest, testUndoReorderingMulti)
 {
     // Create two views and a document of 2 paragraphs.
diff --git a/sw/source/core/undo/docundo.cxx b/sw/source/core/undo/docundo.cxx
index 84fcd4fe5bb6..a9efc248259a 100644
--- a/sw/source/core/undo/docundo.cxx
+++ b/sw/source/core/undo/docundo.cxx
@@ -416,7 +416,7 @@ bool UndoManager::IsViewUndoActionIndependent(const SwView* pView, sal_uInt16& r
     for (size_t i = 0; i < GetRedoActionCount(); ++i)
     {
         auto pRedoAction = dynamic_cast<const SwUndo*>(GetRedoAction(i));
-        if (!pRedoAction || pViewSwAction->GetId() != SwUndoId::TYPING)
+        if (!pRedoAction || pRedoAction->GetId() != SwUndoId::TYPING)
         {
             return false;
         }