4 files changed, 16 insertions, 3 deletions
diff --git a/core/fpdfapi/page/cpdf_image.cpp b/core/fpdfapi/page/cpdf_image.cpp
index 8ce4185446..b74de62250 100644
--- a/core/fpdfapi/page/cpdf_image.cpp
+++ b/core/fpdfapi/page/cpdf_image.cpp
@@ -331,7 +331,13 @@ RetainPtr<CFX_DIBSource> CPDF_Image::LoadDIBSource() const {
   if (!source->Load(m_pDocument.Get(), m_pStream.Get()))
     return nullptr;
 
-  return source;
+  if (!source->IsJBigImage())
+    return source;
+
+  CPDF_DIBSource::LoadState ret = CPDF_DIBSource::LoadState::kContinue;
+  while (ret == CPDF_DIBSource::LoadState::kContinue)
+    ret = source->ContinueLoadDIBSource(nullptr);
+  return ret == CPDF_DIBSource::LoadState::kSuccess ? source : nullptr;
 }
 
 RetainPtr<CFX_DIBSource> CPDF_Image::DetachBitmap() {
diff --git a/core/fpdfapi/render/cpdf_dibsource.cpp b/core/fpdfapi/render/cpdf_dibsource.cpp
index 8a752374b6..3c8d471767 100644
--- a/core/fpdfapi/render/cpdf_dibsource.cpp
+++ b/core/fpdfapi/render/cpdf_dibsource.cpp
@@ -708,6 +708,10 @@ RetainPtr<CPDF_DIBSource> CPDF_DIBSource::DetachMask() {
   return std::move(m_pMask);
 }
 
+bool CPDF_DIBSource::IsJBigImage() const {
+  return m_pStreamAcc->GetImageDecoder() == "JBIG2Decode";
+}
+
 CPDF_DIBSource::LoadState CPDF_DIBSource::StartLoadMaskDIB() {
   m_pMask = pdfium::MakeRetain<CPDF_DIBSource>();
   LoadState ret = m_pMask->StartLoadDIBSource(
diff --git a/core/fpdfapi/render/cpdf_dibsource.h b/core/fpdfapi/render/cpdf_dibsource.h
index a3e44c57e7..a29385f6ad 100644
--- a/core/fpdfapi/render/cpdf_dibsource.h
+++ b/core/fpdfapi/render/cpdf_dibsource.h
@@ -76,6 +76,8 @@ class CPDF_DIBSource : public CFX_DIBSource {
   LoadState ContinueLoadDIBSource(IFX_PauseIndicator* pPause);
   RetainPtr<CPDF_DIBSource> DetachMask();
 
+  bool IsJBigImage() const;
+
  private:
   CPDF_DIBSource();
 
diff --git a/core/fxge/dib/cfx_dibsource.cpp b/core/fxge/dib/cfx_dibsource.cpp
index f96ca1e074..104b3caf96 100644
--- a/core/fxge/dib/cfx_dibsource.cpp
+++ b/core/fxge/dib/cfx_dibsource.cpp
@@ -1225,12 +1225,13 @@ bool CFX_DIBSource::ConvertBuffer(
     }
     case FXDIB_8bppRgb:
     case FXDIB_8bppRgba: {
-      if (bpp == 8 && !pSrcBitmap->GetPalette()) {
+      const bool bpp_1_or_8 = (bpp == 1 || bpp == 8);
+      if (bpp_1_or_8 && !pSrcBitmap->GetPalette()) {
         return ConvertBuffer(FXDIB_8bppMask, dest_buf, dest_pitch, width,
                              height, pSrcBitmap, src_left, src_top, p_pal);
       }
       p_pal->reset(FX_Alloc(uint32_t, 256));
-      if ((bpp == 1 || bpp == 8) && pSrcBitmap->GetPalette()) {
+      if (bpp_1_or_8 && pSrcBitmap->GetPalette()) {
         ConvertBuffer_Plt2PltRgb8(dest_buf, dest_pitch, width, height,
                                   pSrcBitmap, src_left, src_top, p_pal->get());
         return true;