Fix lifetime issue in CCodec_ProgressiveDecoder.

The associated bug is caused by failure to clean up context before
returing at line 740 or so. But cleanups are fragile, so instead
do not move context out of a local until success. This in turn
means passing the local to one helper rather that using the stored
value and confirming this is the only helper method invoked during
the time in which the context is not yet stored.

Bug: 879025
Change-Id: I1acb438edc28f7f4dd8acccc2461fe3a5ea7f5c8
Reviewed-on: https://pdfium-review.googlesource.com/41670
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

2 files changed, 18 insertions, 17 deletions

diff --git a/core/fxcodec/codec/ccodec_progressivedecoder.cpp b/core/fxcodec/codec/ccodec_progressivedecoder.cpp
index 3426c66e47..6faaaa11cd 100644
--- a/core/fxcodec/codec/ccodec_progressivedecoder.cpp
+++ b/core/fxcodec/codec/ccodec_progressivedecoder.cpp
@@ -579,7 +579,8 @@ void CCodec_ProgressiveDecoder::GifReadScanline(int32_t row_num,
 bool CCodec_ProgressiveDecoder::BmpInputImagePositionBuf(uint32_t rcd_pos) {
   m_offSet = rcd_pos;
   FXCODEC_STATUS error_status = FXCODEC_STATUS_ERROR;
-  return BmpReadMoreData(m_pCodecMgr->GetBmpModule(), error_status);
+  return BmpReadMoreData(m_pCodecMgr->GetBmpModule(), m_pBmpContext.get(),
+                         error_status);
 }
 
 void CCodec_ProgressiveDecoder::BmpReadScanline(
@@ -715,8 +716,9 @@ bool CCodec_ProgressiveDecoder::BmpDetectImageType(CFX_DIBAttribute* pAttribute,
     return false;
   }
 
-  m_pBmpContext = pBmpModule->Start(this);
-  if (!m_pBmpContext) {
+  std::unique_ptr<CCodec_BmpModule::Context> pBmpContext =
+      pBmpModule->Start(this);
+  if (!pBmpContext) {
     m_status = FXCODEC_STATUS_ERR_MEMORY;
     return false;
   }
@@ -727,24 +729,23 @@ bool CCodec_ProgressiveDecoder::BmpDetectImageType(CFX_DIBAttribute* pAttribute,
   }
 
   m_offSet += size;
-  pBmpModule->Input(m_pBmpContext.get(), {m_pSrcBuf.get(), size});
+  pBmpModule->Input(pBmpContext.get(), {m_pSrcBuf.get(), size});
   std::vector<uint32_t> palette;
   int32_t readResult = pBmpModule->ReadHeader(
-      m_pBmpContext.get(), &m_SrcWidth, &m_SrcHeight, &m_BmpIsTopBottom,
+      pBmpContext.get(), &m_SrcWidth, &m_SrcHeight, &m_BmpIsTopBottom,
       &m_SrcComponents, &m_SrcPaletteNumber, &palette, pAttribute);
   while (readResult == 2) {
     FXCODEC_STATUS error_status = FXCODEC_STATUS_ERR_FORMAT;
-    if (!BmpReadMoreData(pBmpModule, error_status)) {
+    if (!BmpReadMoreData(pBmpModule, pBmpContext.get(), error_status)) {
       m_status = error_status;
       return false;
     }
     readResult = pBmpModule->ReadHeader(
-        m_pBmpContext.get(), &m_SrcWidth, &m_SrcHeight, &m_BmpIsTopBottom,
+        pBmpContext.get(), &m_SrcWidth, &m_SrcHeight, &m_BmpIsTopBottom,
         &m_SrcComponents, &m_SrcPaletteNumber, &palette, pAttribute);
   }
 
   if (readResult != 1) {
-    m_pBmpContext.reset();
     m_status = FXCODEC_STATUS_ERR_FORMAT;
     return false;
   }
@@ -764,7 +765,6 @@ bool CCodec_ProgressiveDecoder::BmpDetectImageType(CFX_DIBAttribute* pAttribute,
       format = FXDIB_Rgb32;
       break;
     default:
-      m_pBmpContext.reset();
       m_status = FXCODEC_STATUS_ERR_FORMAT;
       return false;
   }
@@ -773,20 +773,19 @@ bool CCodec_ProgressiveDecoder::BmpDetectImageType(CFX_DIBAttribute* pAttribute,
   uint32_t neededData = 0;
   if (!CFX_DIBitmap::CalculatePitchAndSize(m_SrcWidth, m_SrcHeight, format,
                                            &pitch, &neededData)) {
-    m_pBmpContext.reset();
     m_status = FXCODEC_STATUS_ERR_FORMAT;
     return false;
   }
 
   uint32_t availableData = m_SrcSize > m_offSet ? m_SrcSize - m_offSet : 0;
   if (neededData > availableData) {
-    m_pBmpContext.reset();
     m_status = FXCODEC_STATUS_ERR_FORMAT;
     return false;
   }
 
   m_SrcBPC = 8;
   m_clipBox = FX_RECT(0, 0, m_SrcWidth, m_SrcHeight);
+  m_pBmpContext = std::move(pBmpContext);
   if (m_SrcPaletteNumber) {
     m_pSrcPalette.reset(FX_Alloc(FX_ARGB, m_SrcPaletteNumber));
     memcpy(m_pSrcPalette.get(), palette.data(),
@@ -797,15 +796,16 @@ bool CCodec_ProgressiveDecoder::BmpDetectImageType(CFX_DIBAttribute* pAttribute,
   return true;
 }
 
-bool CCodec_ProgressiveDecoder::BmpReadMoreData(CCodec_BmpModule* pBmpModule,
-                                                FXCODEC_STATUS& err_status) {
+bool CCodec_ProgressiveDecoder::BmpReadMoreData(
+    CCodec_BmpModule* pBmpModule,
+    CCodec_BmpModule::Context* pBmpContext,
+    FXCODEC_STATUS& err_status) {
   uint32_t dwSize = (uint32_t)m_pFile->GetSize();
   if (dwSize <= m_offSet)
     return false;
 
   dwSize = dwSize - m_offSet;
-  FX_SAFE_UINT32 avail_input =
-      pBmpModule->GetAvailInput(m_pBmpContext.get(), nullptr);
+  FX_SAFE_UINT32 avail_input = pBmpModule->GetAvailInput(pBmpContext, nullptr);
   if (!avail_input.IsValid())
     return false;
 
@@ -835,7 +835,7 @@ bool CCodec_ProgressiveDecoder::BmpReadMoreData(CCodec_BmpModule* pBmpModule,
     return false;
   }
   m_offSet += dwSize;
-  pBmpModule->Input(m_pBmpContext.get(), {m_pSrcBuf.get(), dwSize + dwAvail});
+  pBmpModule->Input(pBmpContext, {m_pSrcBuf.get(), dwSize + dwAvail});
   return true;
 }
 
@@ -869,7 +869,7 @@ FXCODEC_STATUS CCodec_ProgressiveDecoder::BmpContinueDecode() {
     int32_t readRes = pBmpModule->LoadImage(m_pBmpContext.get());
     while (readRes == 2) {
       FXCODEC_STATUS error_status = FXCODEC_STATUS_DECODE_FINISH;
-      if (!BmpReadMoreData(pBmpModule, error_status)) {
+      if (!BmpReadMoreData(pBmpModule, m_pBmpContext.get(), error_status)) {
         m_pDeviceBitmap = nullptr;
         m_pFile = nullptr;
         m_status = error_status;
diff --git a/core/fxcodec/codec/ccodec_progressivedecoder.h b/core/fxcodec/codec/ccodec_progressivedecoder.h
index 4216a84a51..1f72d9f044 100644
--- a/core/fxcodec/codec/ccodec_progressivedecoder.h
+++ b/core/fxcodec/codec/ccodec_progressivedecoder.h
@@ -182,6 +182,7 @@ class CCodec_ProgressiveDecoder :
  private:
 #ifdef PDF_ENABLE_XFA_BMP
   bool BmpReadMoreData(CCodec_BmpModule* pBmpModule,
+                       CCodec_BmpModule::Context* pBmpContext,
                        FXCODEC_STATUS& err_status);
   bool BmpDetectImageType(CFX_DIBAttribute* pAttribute, uint32_t size);
   FXCODEC_STATUS BmpStartDecode(const RetainPtr<CFX_DIBitmap>& pDIBitmap);