Fix infinite recursion in CPDF_Parser::ParseIndirectObjectAt().
A suitably corrupted file can cause the parser(s) to repeatedly re-read
sections of the file at increasing parser recursion depth until the
stack is exhausted. There is supposed to be a check for this based upon
the parser "level", but not all call paths pass or update the level as
required.
Much as I hate per-class statics, this introduces one to track the depth
so that the check is enforced no matter how screwy the call path might be
that leads the parser to re-enter itself. This is more palatable than trying
to find all these paths and fix them. We know this is OK since there is
only one thread in here modifying the static.
BUG=451830
R=thestig@chromium.org
Review URL: https://codereview.chromium.org/875263002
diff --git a/core/include/fpdfapi/fpdf_parser.h b/core/include/fpdfapi/fpdf_parser.h
index 3f9bda5..e1a0f5c 100644
--- a/core/include/fpdfapi/fpdf_parser.h
+++ b/core/include/fpdfapi/fpdf_parser.h
@@ -261,10 +261,10 @@
m_Pos = pos;
}
- CPDF_Object* GetObject(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum, int level, struct PARSE_CONTEXT* pContext = NULL, FX_BOOL bDecrypt = TRUE);
+ CPDF_Object* GetObject(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum, struct PARSE_CONTEXT* pContext = NULL, FX_BOOL bDecrypt = TRUE);
- CPDF_Object* GetObjectByStrict(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum, int level, struct PARSE_CONTEXT* pContext = NULL);
+ CPDF_Object* GetObjectByStrict(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum, struct PARSE_CONTEXT* pContext = NULL);
int GetDirectNum();
@@ -302,6 +302,8 @@
CFX_ByteString GetNextWord(FX_BOOL& bIsNumber);
protected:
+ static const int kParserMaxRecursionDepth = 64;
+ static int s_CurrentRecursionDepth;
virtual FX_BOOL GetNextChar(FX_BYTE& ch);
@@ -520,7 +522,6 @@
return m_dwFirstPageNo;
}
protected:
-
CPDF_Document* m_pDocument;
CPDF_SyntaxParser m_Syntax;
diff --git a/core/include/fxcrt/fx_basic.h b/core/include/fxcrt/fx_basic.h
index 62324f5..7ad44c6 100644
--- a/core/include/fxcrt/fx_basic.h
+++ b/core/include/fxcrt/fx_basic.h
@@ -1414,6 +1414,21 @@
CFX_DataFilter* m_pDestFilter;
};
+
+template<typename T>
+class CFX_AutoRestorer {
+public:
+ explicit CFX_AutoRestorer(T* location) {
+ m_Location = location;
+ m_OldValue = *location;
+ }
+ ~CFX_AutoRestorer() { *m_Location = m_OldValue; }
+
+private:
+ T* m_Location;
+ T m_OldValue;
+};
+
template <class T>
class CFX_SmartPointer
{
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 5dfcc82..8195989 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -12,7 +12,6 @@
#include <utility>
#include <vector>
-#define _PARSER_OBJECT_LEVLE_ 64
extern const FX_LPCSTR _PDF_CharType;
FX_BOOL IsSignatureDict(const CPDF_Dictionary* pDict)
{
@@ -39,6 +38,7 @@
}
return 0;
}
+
CPDF_Parser::CPDF_Parser()
{
m_pDocument = NULL;
@@ -1217,7 +1217,7 @@
FX_DWORD thisoff = syntax.GetDirectNum();
if (thisnum == objnum) {
syntax.RestorePos(offset + thisoff);
- pRet = syntax.GetObject(pObjList, 0, 0, 0, pContext);
+ pRet = syntax.GetObject(pObjList, 0, 0, pContext);
break;
}
n --;
@@ -1396,7 +1396,7 @@
m_Syntax.RestorePos(SavedPos);
return NULL;
}
- CPDF_Object* pObj = m_Syntax.GetObject(pObjList, objnum, parser_gennum, 0, pContext);
+ CPDF_Object* pObj = m_Syntax.GetObject(pObjList, objnum, parser_gennum, pContext);
FX_FILESIZE endOffset = m_Syntax.SavePos();
CFX_ByteString bsWord = m_Syntax.GetKeyword();
if (bsWord == FX_BSTRC("endobj")) {
@@ -1437,7 +1437,7 @@
m_Syntax.RestorePos(SavedPos);
return NULL;
}
- CPDF_Object* pObj = m_Syntax.GetObjectByStrict(pObjList, objnum, gennum, 0, pContext);
+ CPDF_Object* pObj = m_Syntax.GetObjectByStrict(pObjList, objnum, gennum, pContext);
if (pResultPos) {
*pResultPos = m_Syntax.m_Pos;
}
@@ -1676,6 +1676,10 @@
m_Syntax.m_MetadataObjnum = dwSaveMetadataObjnum;
return PDFPARSE_ERROR_SUCCESS;
}
+
+// static
+int CPDF_SyntaxParser::s_CurrentRecursionDepth = 0;
+
CPDF_SyntaxParser::CPDF_SyntaxParser()
{
m_pFileAccess = NULL;
@@ -2049,9 +2053,10 @@
GetNextWord();
return CFX_ByteString((FX_LPCSTR)m_WordBuffer, m_WordSize);
}
-CPDF_Object* CPDF_SyntaxParser::GetObject(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum, FX_INT32 level, PARSE_CONTEXT* pContext, FX_BOOL bDecrypt)
+CPDF_Object* CPDF_SyntaxParser::GetObject(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum, PARSE_CONTEXT* pContext, FX_BOOL bDecrypt)
{
- if (level > _PARSER_OBJECT_LEVLE_) {
+ CFX_AutoRestorer<int> restorer(&s_CurrentRecursionDepth);
+ if (++s_CurrentRecursionDepth > kParserMaxRecursionDepth) {
return NULL;
}
FX_FILESIZE SavedPos = m_Pos;
@@ -2136,7 +2141,7 @@
}
CPDF_Array* pArray = CPDF_Array::Create();
while (1) {
- CPDF_Object* pObj = GetObject(pObjList, objnum, gennum, level + 1);
+ CPDF_Object* pObj = GetObject(pObjList, objnum, gennum);
if (pObj == NULL) {
return pArray;
}
@@ -2188,7 +2193,7 @@
if (key == FX_BSTRC("/Contents")) {
dwSignValuePos = m_Pos;
}
- CPDF_Object* pObj = GetObject(pObjList, objnum, gennum, level + 1);
+ CPDF_Object* pObj = GetObject(pObjList, objnum, gennum);
if (pObj == NULL) {
continue;
}
@@ -2203,7 +2208,7 @@
if (IsSignatureDict(pDict)) {
FX_FILESIZE dwSavePos = m_Pos;
m_Pos = dwSignValuePos;
- CPDF_Object* pObj = GetObject(pObjList, objnum, gennum, level + 1, NULL, FALSE);
+ CPDF_Object* pObj = GetObject(pObjList, objnum, gennum, NULL, FALSE);
pDict->SetAt(FX_BSTRC("Contents"), pObj);
m_Pos = dwSavePos;
}
@@ -2238,10 +2243,10 @@
}
return NULL;
}
-CPDF_Object* CPDF_SyntaxParser::GetObjectByStrict(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum,
- FX_INT32 level, struct PARSE_CONTEXT* pContext)
+CPDF_Object* CPDF_SyntaxParser::GetObjectByStrict(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, FX_DWORD gennum, struct PARSE_CONTEXT* pContext)
{
- if (level > _PARSER_OBJECT_LEVLE_) {
+ CFX_AutoRestorer<int> restorer(&s_CurrentRecursionDepth);
+ if (++s_CurrentRecursionDepth > kParserMaxRecursionDepth) {
return NULL;
}
FX_FILESIZE SavedPos = m_Pos;
@@ -2318,7 +2323,7 @@
}
CPDF_Array* pArray = CPDF_Array::Create();
while (1) {
- CPDF_Object* pObj = GetObject(pObjList, objnum, gennum, level + 1);
+ CPDF_Object* pObj = GetObject(pObjList, objnum, gennum);
if (pObj == NULL) {
if (m_WordBuffer[0] == ']') {
return pArray;
@@ -2364,7 +2369,7 @@
continue;
}
key = PDF_NameDecode(key);
- CPDF_Object* pObj = GetObject(pObjList, objnum, gennum, level + 1);
+ CPDF_Object* pObj = GetObject(pObjList, objnum, gennum);
if (pObj == NULL) {
if (pDict)
pDict->Release();
diff --git a/fpdfsdk/src/fpdfview_embeddertest.cpp b/fpdfsdk/src/fpdfview_embeddertest.cpp
index ee32727..14a6532 100644
--- a/fpdfsdk/src/fpdfview_embeddertest.cpp
+++ b/fpdfsdk/src/fpdfview_embeddertest.cpp
@@ -177,3 +177,8 @@
dest = FPDF_GetNamedDestByName(document(), "Bogus");
EXPECT_EQ(nullptr, dest);
}
+
+// The following tests pass if the document opens without crashing.
+TEST_F(FPDFViewEmbeddertest, Crashers) {
+ EXPECT_TRUE(OpenDocument("testing/resources/bug_451830.pdf"));
+}
diff --git a/testing/resources/bug_451830.pdf b/testing/resources/bug_451830.pdf
new file mode 100644
index 0000000..f209bb3
--- /dev/null
+++ b/testing/resources/bug_451830.pdf
@@ -0,0 +1,14 @@
+%PDF-1.2
+%âãÏÓ
+7 0 obj <<
+ /Type /Font
+trailer
+<<///
+endobj
+4 0 obj <<
+ /Resources <<
+ /FT 7 0 R
+>>
+endstream
+endobj
+%%EOF
