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authorDan Sinclair <dsinclair@chromium.org>2018-03-07 20:44:47 +0000
committerChromium commit bot <commit-bot@chromium.org>2018-03-07 20:44:47 +0000
commit04d792fb7510e328f508bc81379ca15791af93e7 (patch)
treeabf0a67ef0769eaaaef9c8443ec317bd523472a9 /xfa/fxfa/fm2js
parent749b609d11e855edf0aefdacbe4f81bb73d8d0d0 (diff)
downloadpdfium-04d792fb7510e328f508bc81379ca15791af93e7.tar.xz
[formcalc] Consider width along with depth of tree
When building the formcalc parser trees we need to limit on width along with depth. It's possible to generate a tree of a single depth but is more then 20k nodes wide. This will eventuall cause stack overflow issues. This CL re-uses the depth check for the grammar expressions in which we're extending the width of the tree we count that against our depth check. Bug: chromium:813346 Change-Id: I01f6567a75776a75374465eacc1ff546db46cac1 Reviewed-on: https://pdfium-review.googlesource.com/28170 Reviewed-by: Ryan Harrison <rharrison@chromium.org> Reviewed-by: Henrique Nakashima <hnakashima@chromium.org> Commit-Queue: dsinclair <dsinclair@chromium.org>
Diffstat (limited to 'xfa/fxfa/fm2js')
-rw-r--r--xfa/fxfa/fm2js/cxfa_fmparser.cpp31
-rw-r--r--xfa/fxfa/fm2js/cxfa_fmparser_unittest.cpp19
2 files changed, 45 insertions, 5 deletions
diff --git a/xfa/fxfa/fm2js/cxfa_fmparser.cpp b/xfa/fxfa/fm2js/cxfa_fmparser.cpp
index 20e0fa6d1c..5079ab110e 100644
--- a/xfa/fxfa/fm2js/cxfa_fmparser.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fmparser.cpp
@@ -273,6 +273,9 @@ CXFA_FMParser::ParseLogicalOrExpression() {
// TODO(dsinclair): Is this for() needed?
for (;;) {
+ if (!IncrementParseDepthAndCheck())
+ return nullptr;
+
switch (m_token.m_type) {
case TOKor:
case TOKksor: {
@@ -310,6 +313,9 @@ CXFA_FMParser::ParseLogicalAndExpression() {
// TODO(dsinclair): Is this for() needed?
for (;;) {
+ if (!IncrementParseDepthAndCheck())
+ return nullptr;
+
switch (m_token.m_type) {
case TOKand:
case TOKksand: {
@@ -346,32 +352,38 @@ CXFA_FMParser::ParseEqualityExpression() {
// TODO(dsinclair): Is this for() needed?
for (;;) {
- std::unique_ptr<CXFA_FMSimpleExpression> e2;
+ if (!IncrementParseDepthAndCheck())
+ return nullptr;
+
switch (m_token.m_type) {
case TOKeq:
- case TOKkseq:
+ case TOKkseq: {
if (!NextToken())
return nullptr;
- e2 = ParseRelationalExpression();
+ std::unique_ptr<CXFA_FMSimpleExpression> e2 =
+ ParseRelationalExpression();
if (!e2)
return nullptr;
e1 = pdfium::MakeUnique<CXFA_FMEqualExpression>(TOKeq, std::move(e1),
std::move(e2));
continue;
+ }
case TOKne:
- case TOKksne:
+ case TOKksne: {
if (!NextToken())
return nullptr;
- e2 = ParseRelationalExpression();
+ std::unique_ptr<CXFA_FMSimpleExpression> e2 =
+ ParseRelationalExpression();
if (!e2)
return nullptr;
e1 = pdfium::MakeUnique<CXFA_FMNotEqualExpression>(TOKne, std::move(e1),
std::move(e2));
continue;
+ }
default:
break;
}
@@ -394,6 +406,9 @@ CXFA_FMParser::ParseRelationalExpression() {
// TODO(dsinclair): Is this for() needed?
for (;;) {
+ if (!IncrementParseDepthAndCheck())
+ return nullptr;
+
std::unique_ptr<CXFA_FMSimpleExpression> e2;
switch (m_token.m_type) {
case TOKlt:
@@ -466,6 +481,9 @@ CXFA_FMParser::ParseAddtiveExpression() {
// TODO(dsinclair): Is this for() needed?
for (;;) {
+ if (!IncrementParseDepthAndCheck())
+ return nullptr;
+
std::unique_ptr<CXFA_FMSimpleExpression> e2;
switch (m_token.m_type) {
case TOKplus:
@@ -512,6 +530,9 @@ CXFA_FMParser::ParseMultiplicativeExpression() {
// TODO(dsinclair): Is this for() needed?
for (;;) {
+ if (!IncrementParseDepthAndCheck())
+ return nullptr;
+
std::unique_ptr<CXFA_FMSimpleExpression> e2;
switch (m_token.m_type) {
case TOKmul:
diff --git a/xfa/fxfa/fm2js/cxfa_fmparser_unittest.cpp b/xfa/fxfa/fm2js/cxfa_fmparser_unittest.cpp
index 5ee27b189e..1eedebfcca 100644
--- a/xfa/fxfa/fm2js/cxfa_fmparser_unittest.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fmparser_unittest.cpp
@@ -238,3 +238,22 @@ TEST(CXFA_FMParserTest, ParseBadElseIfExpression) {
ASSERT_TRUE(ast == nullptr);
EXPECT_TRUE(parser->HasError());
}
+
+TEST(CXFA_FMParserTest, ParseDepthWithWideTree) {
+ const wchar_t input[] = {L"a <> b <> c <> d <> e <> f <> g <> h <> i <> j"};
+
+ {
+ auto parser = pdfium::MakeUnique<CXFA_FMParser>(input);
+ std::unique_ptr<CXFA_FMAST> ast = parser->Parse();
+ ASSERT_TRUE(ast);
+ EXPECT_TRUE(!parser->HasError());
+ }
+
+ {
+ auto parser = pdfium::MakeUnique<CXFA_FMParser>(input);
+ parser->SetMaxParseDepthForTest(5);
+ std::unique_ptr<CXFA_FMAST> ast = parser->Parse();
+ ASSERT_TRUE(ast == nullptr);
+ EXPECT_TRUE(parser->HasError());
+ }
+}