Verify image dimentions before using

core/fpdfapi/fpdf_render/fpdf_render_image.cpp

Index: core/fpdfapi/fpdf_render/fpdf_render_image.cpp
diff --git a/core/fpdfapi/fpdf_render/fpdf_render_image.cpp b/core/fpdfapi/fpdf_render/fpdf_render_image.cpp
index e7e96823220c88af7ccb740daa04ea62382a7a2a..e23cab3546c57eaa5076d292ea01db2b8b3ba97a 100644
--- a/core/fpdfapi/fpdf_render/fpdf_render_image.cpp
+++ b/core/fpdfapi/fpdf_render/fpdf_render_image.cpp
@@ -366,6 +366,9 @@ CPDF_ImageRenderer::~CPDF_ImageRenderer() {
 FX_BOOL CPDF_ImageRenderer::StartLoadDIBSource() {
   CFX_FloatRect image_rect_f = m_ImageMatrix.GetUnitRect();
   FX_RECT image_rect = image_rect_f.GetOuterRect();
+  if (!image_rect.Valid())
+    return FALSE;
+
   int dest_width = image_rect.Width();
   int dest_height = image_rect.Height();
   if (m_ImageMatrix.a < 0) {