Check for negative page size in FindTextlineFlowOrientation()

core/fpdftext/cpdf_textpage.cpp

Index: core/fpdftext/cpdf_textpage.cpp
diff --git a/core/fpdftext/cpdf_textpage.cpp b/core/fpdftext/cpdf_textpage.cpp
index d88464bfc45278f197a612f56bd7320f10cf840a..b6eb87eea178cbddca2a4e8a311685a592612356 100644
--- a/core/fpdftext/cpdf_textpage.cpp
+++ b/core/fpdftext/cpdf_textpage.cpp
@@ -507,6 +507,9 @@ CPDF_TextPage::TextOrientation CPDF_TextPage::FindTextlineFlowOrientation()
 
   const int32_t nPageWidth = static_cast<int32_t>(m_pPage->GetPageWidth());
   const int32_t nPageHeight = static_cast<int32_t>(m_pPage->GetPageHeight());
+  if (nPageWidth <= 0 || nPageHeight <= 0)
+    return TextOrientation::Unknown;
+
   std::vector<bool> nHorizontalMask(nPageWidth);
   std::vector<bool> nVerticalMask(nPageHeight);
   FX_FLOAT fLineHeight = 0.0f;