From ca8ee545445bb188ef06dd673f8e54eb1088043a Mon Sep 17 00:00:00 2001
From: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Date: Thu, 30 Jan 2025 10:11:21 +0100
Subject: [PATCH] Escape calculating vertical windows-metrics if they're too
 big
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This amends 073fae097ce40bee1532c252a8c696840b5dfc16 which added
an escape before calculating the vertical metrics if they were too
big and would overflow. It missed one spot, which was when using
the winAscent/winDescent instead of the typo-metrics.

Change-Id: Ib6a7705f6676c66bfd04b37efa30fe2d1b99581c
Reviewed-by: Robert Löhning <robert.loehning@qt.io>
(cherry picked from commit f846754663aae1652e4eec9a441ee222af352319)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit e51d03e334b18cd34fbfb708b9835327658f2075)
---
 src/gui/text/qfontengine.cpp                    |  3 +++
 .../gui/text/qfontmetrics/tst_qfontmetrics.cpp  | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index 1dfdeb5ec0..aa19f7d84a 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -469,6 +469,9 @@ bool QFontEngine::processOS2Table() const
             // Some fonts may have invalid OS/2 data. We detect this and bail out.
             if (winAscent == 0 && winDescent == 0)
                 return false;
+            const auto limitForQFixed = std::numeric_limits<int>::max() / (fontDef.pixelSize * 64);
+            if (winAscent > limitForQFixed || winDescent > limitForQFixed)
+                return false;
             m_ascent = QFixed::fromReal(winAscent * fontDef.pixelSize) / unitsPerEm;
             m_descent = QFixed::fromReal(winDescent * fontDef.pixelSize) / unitsPerEm;
             m_leading = QFixed{};
diff --git a/tests/auto/gui/text/qfontmetrics/tst_qfontmetrics.cpp b/tests/auto/gui/text/qfontmetrics/tst_qfontmetrics.cpp
index bad33ab0a4..f056cc9fb1 100644
--- a/tests/auto/gui/text/qfontmetrics/tst_qfontmetrics.cpp
+++ b/tests/auto/gui/text/qfontmetrics/tst_qfontmetrics.cpp
@@ -37,6 +37,7 @@ private slots:
     void largeText_data();
     void largeText(); // QTBUG-123339
     void typoLineMetrics();
+    void hugeFontMetrics();
 };
 
 void tst_QFontMetrics::same()
@@ -454,5 +455,21 @@ void tst_QFontMetrics::typoLineMetrics()
     }
 }
 
+void tst_QFontMetrics::hugeFontMetrics()
+{
+    QFont bigFont;
+    bigFont.setPixelSize(10000);
+
+    QFont hugeFont;
+    hugeFont.setPixelSize(32000);
+
+    QFont hugeFontWithTypoLineMetrics;
+    hugeFontWithTypoLineMetrics.setStyleStrategy(QFont::PreferTypoLineMetrics);
+    hugeFontWithTypoLineMetrics.setPixelSize(30000);
+
+    QVERIFY(QFontMetricsF(bigFont).height() < QFontMetricsF(hugeFont).height());
+    QVERIFY(QFontMetricsF(bigFont).height() < QFontMetricsF(hugeFontWithTypoLineMetrics).height());
+}
+
 QTEST_MAIN(tst_QFontMetrics)
 #include "tst_qfontmetrics.moc"