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tst_QTextEdit: fix UB (invalid downcast) in various functions

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The test uses the old-but-invalid trick of inheriting from a class X
to gain access to its private or protected parts, but then just
casting an object of dynamic type X to the newly derived class. This
is invalid, because the object is not actually of the newly-derived
type.

Says UBSan (excerpt):

  tst_qtextedit.cpp:2273:5: runtime error: downcast of address 0x60400013c190 which does not point to an object of type 'PublicTextEdit'
  0x60400013c190: note: object is of type 'QTextEdit'
   00 00 00 00  70 bc 57 df b1 7f 00 00  80 66 30 00 90 61 00 00  70 be 57 df b1 7f 00 00  00 00 be be
                ^~~~~~~~~~~~~~~~~~~~~~~
                vptr for 'QTextEdit'

To fix, make QTextEdit befriend tst_QTextEdit. This is how we do it
elsewhere, too. Then remove the now-unused PublicTextEdit helper.

Amends the start of the public history, and, in one function,
56f0ebfe860e440dcbba8997f44836debc901119 (which is only in Qt 6.4+, so
the cherry-pick to 5.15 will have to drop the part in pasteFromMarkdown().

Pick-to: 6.9 6.8 6.5 5.15
Change-Id: I967238d84cae0f6dd8f05d0afb7a318292d96415
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
This commit is contained in:
Marc Mutz 2025-03-30 19:36:21 +02:00
parent de2de7e12c
commit 73fc32af14
2 changed files with 6 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
src/widgets/widgets/qtextedit.h
View File

@ -13,6 +13,8 @@
QT_REQUIRE_CONFIG(textedit);
class tst_QTextEdit;
QT_BEGIN_NAMESPACE
class QStyleSheet;
@ -283,6 +285,7 @@ private:
friend class QTextEditControl;
friend class QTextDocument;
friend class QWidgetTextControl;
friend class ::tst_QTextEdit;
};
Q_DECLARE_OPERATORS_FOR_FLAGS(QTextEdit::AutoFormatting)

13
tests/auto/widgets/widgets/qtextedit/tst_qtextedit.cpp
View File

@ -2256,13 +2256,6 @@ void tst_QTextEdit::setDocumentPreservesPalette()
}
#endif
class PublicTextEdit : public QTextEdit
{
public:
void publicInsertFromMimeData(const QMimeData *source)
{ insertFromMimeData(source); }
};
void tst_QTextEdit::pasteFromQt3RichText()
{
QByteArray richtext("<!--StartFragment--><p> QTextEdit is an ");
@ -2270,7 +2263,7 @@ void tst_QTextEdit::pasteFromQt3RichText()
QMimeData mimeData;
mimeData.setData("application/x-qrichtext", richtext);
static_cast<PublicTextEdit *>(ed)->publicInsertFromMimeData(&mimeData);
ed->insertFromMimeData(&mimeData);
QCOMPARE(ed->toPlainText(), QString::fromLatin1(" QTextEdit is an "));
ed->clear();
@ -2278,7 +2271,7 @@ void tst_QTextEdit::pasteFromQt3RichText()
richtext = "<!--StartFragment--> QTextEdit is an ";
mimeData.setData("application/x-qrichtext", richtext);
static_cast<PublicTextEdit *>(ed)->publicInsertFromMimeData(&mimeData);
ed->insertFromMimeData(&mimeData);
QCOMPARE(ed->toPlainText(), QString::fromLatin1(" QTextEdit is an "));
}
@ -2290,7 +2283,7 @@ void tst_QTextEdit::pasteFromMarkdown()
QMimeData mimeData;
mimeData.setData("text/markdown", richtext);
static_cast<PublicTextEdit *>(ed)->publicInsertFromMimeData(&mimeData);
ed->insertFromMimeData(&mimeData);
QCOMPARE(ed->toPlainText(), "This text is rich");
#if QT_CONFIG(textmarkdownwriter)