Fix some more span/memcpy interactions.

Use the preferred idiom of creating a subspan, which makes the
proper checks prior to the copy.

Change-Id: Ia7f25b5760dea5707df66cf421195b23a1ce0ad0
Reviewed-on: https://pdfium-review.googlesource.com/41911
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/core/fpdfapi/page/cpdf_streamparser.cpp b/core/fpdfapi/page/cpdf_streamparser.cpp
index 0d45ed0323..9533bb2a17 100644
--- a/core/fpdfapi/page/cpdf_streamparser.cpp
+++ b/core/fpdfapi/page/cpdf_streamparser.cpp
@@ -177,7 +177,8 @@ std::unique_ptr<CPDF_Stream> CPDF_StreamParser::ReadInlineStream(
     if (OrigSize > m_pBuf.size() - m_Pos)
       OrigSize = m_pBuf.size() - m_Pos;
     pData.reset(FX_Alloc(uint8_t, OrigSize));
-    memcpy(pData.get(), &m_pBuf[m_Pos], OrigSize);
+    auto copy_span = m_pBuf.subspan(m_Pos, OrigSize);
+    memcpy(pData.get(), copy_span.data(), copy_span.size());
     dwStreamSize = OrigSize;
     m_Pos += OrigSize;
   } else {
@@ -209,7 +210,8 @@ std::unique_ptr<CPDF_Stream> CPDF_StreamParser::ReadInlineStream(
     }
     m_Pos = dwSavePos;
     pData.reset(FX_Alloc(uint8_t, dwStreamSize));
-    memcpy(pData.get(), &m_pBuf[m_Pos], dwStreamSize);
+    auto copy_span = m_pBuf.subspan(m_Pos, dwStreamSize);
+    memcpy(pData.get(), copy_span.data(), copy_span.size());
     m_Pos += dwStreamSize;
   }
   pDict->SetNewFor<CPDF_Number>("Length", static_cast<int>(dwStreamSize));