Clear decoders after the image decoder in the /Filter array.

During decoding, when an image decoder is encountered, any
subsequent decoders are ignored, but remain in the array. However,
later on CPDF_DIBSource::ValidateDictParam expects the image
decoder to be the last in the array, causing issues.

A check is also added in CPDF_DIBSource::GetScanline to ensure
that the calculated pitch value is <= the (4-aligned) pitch value in the
cached bitmap to prevent future issues.

Also cleans up some NULL usages.

BUG=552046
R=jun_fang@foxitsoftware.com, tsepez@chromium.org

Review URL: https://codereview.chromium.org/1406943005 .

1 files changed, 5 insertions, 5 deletions

diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp
index bdd5e9aa9c..a7941b4b2d 100644
--- a/core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp
@@ -1084,14 +1084,14 @@ uint8_t* CPDF_DIBSource::GetBuffer() const {
 }
 const uint8_t* CPDF_DIBSource::GetScanline(int line) const {
   if (m_bpc == 0) {
-    return NULL;
+    return nullptr;
   }
   FX_SAFE_DWORD src_pitch = CalculatePitch8(m_bpc, m_nComponents, m_Width);
   if (!src_pitch.IsValid())
-    return NULL;
+    return nullptr;
   FX_DWORD src_pitch_value = src_pitch.ValueOrDie();
-  const uint8_t* pSrcLine = NULL;
-  if (m_pCachedBitmap) {
+  const uint8_t* pSrcLine = nullptr;
+  if (m_pCachedBitmap && src_pitch_value <= m_pCachedBitmap->GetPitch()) {
     if (line >= m_pCachedBitmap->GetHeight()) {
       line = m_pCachedBitmap->GetHeight() - 1;
     }
@@ -1103,7 +1103,7 @@ const uint8_t* CPDF_DIBSource::GetScanline(int line) const {
       pSrcLine = m_pStreamAcc->GetData() + line * src_pitch_value;
     }
   }
-  if (pSrcLine == NULL) {
+  if (!pSrcLine) {
     uint8_t* pLineBuf = m_pMaskedLine ? m_pMaskedLine : m_pLineBuf;
     FXSYS_memset(pLineBuf, 0xFF, m_Pitch);
     return pLineBuf;