Merge to M44: Integer overflow in CJBig2_Image::expand
1. New size should be larger than old size in JBig2_Realloc.
2. Arguments are integers but parameters are size_t in JBIG2_memset.
After integer overflows, it will be presented as a huge
unsigned number on 64 bits system.
BUG=483981
R=brucedawson@chromium.org, tsepez@chromium.org
Review URL: https://codereview.chromium.org/1148643002
(cherry picked from commit e9ccc9bc449846107f1c539e25677f4877ddf22f)
Review URL: https://codereview.chromium.org/1241493002 .
diff --git a/core/src/fxcodec/jbig2/JBig2_Image.cpp b/core/src/fxcodec/jbig2/JBig2_Image.cpp
index 03929b8..8e27bca 100644
--- a/core/src/fxcodec/jbig2/JBig2_Image.cpp
+++ b/core/src/fxcodec/jbig2/JBig2_Image.cpp
@@ -767,18 +767,25 @@
}
void CJBig2_Image::expand(FX_INT32 h, FX_BOOL v)
{
- if (!m_pData) {
+ if (!m_pData || h <= m_nHeight) {
return;
}
- FX_SAFE_DWORD safeMemSize = pdfium::base::checked_cast<FX_DWORD>(h);
- safeMemSize *= pdfium::base::checked_cast<FX_DWORD>(m_nStride);
+ FX_DWORD dwH = pdfium::base::checked_cast<FX_DWORD>(h);
+ FX_DWORD dwStride = pdfium::base::checked_cast<FX_DWORD>(m_nStride);
+ FX_DWORD dwHeight = pdfium::base::checked_cast<FX_DWORD>(m_nHeight);
+ FX_SAFE_DWORD safeMemSize = dwH;
+ safeMemSize *= dwStride;
if (!safeMemSize.IsValid()) {
return;
}
+ //The guaranteed reallocated memory is to be < 4GB (unsigned int).
m_pData = (FX_BYTE*)m_pModule->JBig2_Realloc(m_pData, safeMemSize.ValueOrDie());
- if(h > m_nHeight) {
- JBIG2_memset(m_pData + m_nHeight * m_nStride, v ? 0xff : 0, (h - m_nHeight)*m_nStride);
- }
+ //The result of dwHeight * dwStride doesn't overflow after the
+ //checking of safeMemSize.
+ //The same as the result of (dwH - dwHeight) * dwStride) because
+ //dwH - dwHeight is always less than dwH(h) which is checked in
+ //the calculation of dwH * dwStride.
+ JBIG2_memset(m_pData + dwHeight * dwStride, v ? 0xff : 0, (dwH - dwHeight) * dwStride);
m_nHeight = h;
}
FX_BOOL CJBig2_Image::composeTo_opt2(CJBig2_Image *pDst, FX_INT32 x, FX_INT32 y, JBig2ComposeOp op)
