Fix more integer overflows inside ReadPageHintTable().
BUG=637119
Review-Url: https://codereview.chromium.org/2268693003
diff --git a/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp b/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp
index f1e74dc..18a7b8f 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp
@@ -59,12 +59,12 @@
return false;
// Item 1: The least number of objects in a page.
- uint32_t dwObjLeastNum = hStream->GetBits(32);
+ const uint32_t dwObjLeastNum = hStream->GetBits(32);
if (!dwObjLeastNum)
return FALSE;
// Item 2: The location of the first page's page object.
- uint32_t dwFirstObjLoc = hStream->GetBits(32);
+ const uint32_t dwFirstObjLoc = hStream->GetBits(32);
if (dwFirstObjLoc > static_cast<uint32_t>(nStreamOffset)) {
FX_SAFE_UINT32 safeLoc = pdfium::base::checked_cast<uint32_t>(nStreamLen);
safeLoc += dwFirstObjLoc;
@@ -79,18 +79,18 @@
// Item 3: The number of bits needed to represent the difference
// between the greatest and least number of objects in a page.
- uint32_t dwDeltaObjectsBits = hStream->GetBits(16);
+ const uint32_t dwDeltaObjectsBits = hStream->GetBits(16);
if (!dwDeltaObjectsBits)
return FALSE;
// Item 4: The least length of a page in bytes.
- uint32_t dwPageLeastLen = hStream->GetBits(32);
+ const uint32_t dwPageLeastLen = hStream->GetBits(32);
if (!dwPageLeastLen)
return FALSE;
// Item 5: The number of bits needed to represent the difference
// between the greatest and least length of a page, in bytes.
- uint32_t dwDeltaPageLenBits = hStream->GetBits(16);
+ const uint32_t dwDeltaPageLenBits = hStream->GetBits(16);
if (!dwDeltaPageLenBits)
return FALSE;
@@ -99,11 +99,11 @@
// Item 10: The number of bits needed to represent the greatest
// number of shared object references.
- uint32_t dwSharedObjBits = hStream->GetBits(16);
+ const uint32_t dwSharedObjBits = hStream->GetBits(16);
// Item 11: The number of bits needed to represent the numerically
// greatest shared object identifier used by the pages.
- uint32_t dwSharedIdBits = hStream->GetBits(16);
+ const uint32_t dwSharedIdBits = hStream->GetBits(16);
if (!dwSharedObjBits)
return FALSE;
@@ -111,18 +111,20 @@
// the fractional position for each shared object reference. For each
// shared object referenced from a page, there is an indication of
// where in the page's content stream the object is first referenced.
- uint32_t dwSharedNumeratorBits = hStream->GetBits(16);
+ const uint32_t dwSharedNumeratorBits = hStream->GetBits(16);
if (!dwSharedIdBits)
return FALSE;
// Item 13: Skip Item 13 which has 16 bits.
hStream->SkipBits(16);
- // The maximum number of bits allowed to represent the greatest number of
- // shared object references. 2^39 should be more than enough.
- constexpr uint32_t kMaxSharedObjBits = 39;
- if (dwSharedObjBits > kMaxSharedObjBits)
+ // Sanity check values from the page table header. 2^|kMaxBits| should be more
+ // than enough to represent most of the values here.
+ constexpr uint32_t kMaxBits = 34;
+ if (dwSharedObjBits > kMaxBits || dwDeltaObjectsBits > kMaxBits ||
+ dwSharedIdBits > kMaxBits) {
return false;
+ }
const int nPages = GetNumberOfPages();
if (nPages < 1 || nPages >= FPDF_PAGE_MAX_NUM)
diff --git a/core/fxcrt/fx_basic_buffer.cpp b/core/fxcrt/fx_basic_buffer.cpp
index 91ca6da..5ee1a65 100644
--- a/core/fxcrt/fx_basic_buffer.cpp
+++ b/core/fxcrt/fx_basic_buffer.cpp
@@ -187,24 +187,24 @@
m_BitSize = dwSize * 8;
m_BitPos = 0;
}
+
void CFX_BitStream::ByteAlign() {
- int mod = m_BitPos % 8;
- if (mod == 0) {
- return;
- }
- m_BitPos += 8 - mod;
+ m_BitPos = (m_BitPos + 7) & ~7;
}
+
uint32_t CFX_BitStream::GetBits(uint32_t nBits) {
- if (nBits > m_BitSize || m_BitPos + nBits > m_BitSize) {
+ if (nBits > m_BitSize || m_BitPos + nBits > m_BitSize)
return 0;
- }
+
if (nBits == 1) {
int bit = (m_pData[m_BitPos / 8] & (1 << (7 - m_BitPos % 8))) ? 1 : 0;
m_BitPos++;
return bit;
}
+
uint32_t byte_pos = m_BitPos / 8;
- uint32_t bit_pos = m_BitPos % 8, bit_left = nBits;
+ uint32_t bit_pos = m_BitPos % 8;
+ uint32_t bit_left = nBits;
uint32_t result = 0;
if (bit_pos) {
if (8 - bit_pos >= bit_left) {
@@ -220,9 +220,8 @@
bit_left -= 8;
result |= m_pData[byte_pos++] << bit_left;
}
- if (bit_left) {
+ if (bit_left)
result |= m_pData[byte_pos] >> (8 - bit_left);
- }
m_BitPos += nBits;
return result;
}
@@ -249,12 +248,12 @@
}
int32_t CFX_FileBufferArchive::AppendBlock(const void* pBuf, size_t size) {
- if (!pBuf || size < 1) {
+ if (!pBuf || size < 1)
return 0;
- }
- if (!m_pBuffer) {
+
+ if (!m_pBuffer)
m_pBuffer.reset(FX_Alloc(uint8_t, kBufSize));
- }
+
const uint8_t* buffer = reinterpret_cast<const uint8_t*>(pBuf);
size_t temp_size = size;
while (temp_size) {
