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Add max nest level limit to yaml parser #5275

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Merged
merged 3 commits into from
Mar 5, 2025
Merged

Add max nest level limit to yaml parser #5275

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22c271b
fix fuzzing
yao-msft Mar 5, 2025
3621806
tests
yao-msft Mar 5, 2025
9114ab2
increase limit to 100
yao-msft Mar 5, 2025
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3 changes: 3 additions & 0 deletions src/AppInstallerCLITests/AppInstallerCLITests.vcxproj
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Original file line number Diff line number Diff line change
Expand Up @@ -1040,6 +1040,9 @@
<CopyFileToFolders Include="TestData\ContainsEscapeControlCode.yaml">
<DeploymentContent>true</DeploymentContent>
</CopyFileToFolders>
<CopyFileToFolders Include="TestData\ContainsTooManyNestedLayers.yaml">
<DeploymentContent>true</DeploymentContent>
</CopyFileToFolders>
<CopyFileToFolders Include="TestData\ManifestV1_10-Bad-SchemaHeaderInvalid.yaml">
<DeploymentContent>true</DeploymentContent>
</CopyFileToFolders>
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3 changes: 3 additions & 0 deletions src/AppInstallerCLITests/AppInstallerCLITests.vcxproj.filters
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Expand Up @@ -1053,6 +1053,9 @@
<CopyFileToFolders Include="TestData\ContainsEscapeControlCode.yaml">
<Filter>TestData</Filter>
</CopyFileToFolders>
<CopyFileToFolders Include="TestData\ContainsTooManyNestedLayers.yaml">
<Filter>TestData</Filter>
</CopyFileToFolders>
<CopyFileToFolders Include="TestData\ManifestV1_10-Bad-SchemaHeaderInvalid.yaml">
<Filter>TestData</Filter>
</CopyFileToFolders>
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101 changes: 101 additions & 0 deletions src/AppInstallerCLITests/TestData/ContainsTooManyNestedLayers.yaml
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@@ -0,0 +1,101 @@
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5 changes: 5 additions & 0 deletions src/AppInstallerCLITests/Yaml.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -173,3 +173,8 @@ TEST_CASE("YamlContainsEscapeControlCode", "[YAML]")
{
REQUIRE_THROWS_HR(Load(TestDataFile("ContainsEscapeControlCode.yaml")), APPINSTALLER_CLI_ERROR_LIBYAML_ERROR);
}

TEST_CASE("YamlContainsTooManyNestedLayers", "[YAML]")
{
REQUIRE_THROWS_HR(Load(TestDataFile("ContainsTooManyNestedLayers.yaml")), APPINSTALLER_CLI_ERROR_YAML_DOC_BUILD_FAILED);
}
19 changes: 19 additions & 0 deletions src/AppInstallerSharedLib/YamlWrapper.cpp
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Expand Up @@ -151,6 +151,9 @@ namespace AppInstaller::YAML::Wrapper
size_t childOffset = 0;
};

static int YAML_DOCUMENT_NEST_LEVEL_LIMIT = 100;
int nestLevel = 0;

std::stack<StackItem> resultStack;
resultStack.emplace(root, &result);

Expand All @@ -173,6 +176,12 @@ namespace AppInstaller::YAML::Wrapper
break;
case YAML_SEQUENCE_NODE:
{
if (stackItem.childOffset == 0)
{
// We've entered the sequence.
nestLevel++;
}

yaml_node_item_t* child = stackItem.yamlNode->data.sequence.items.start + stackItem.childOffset++;
if (child < stackItem.yamlNode->data.sequence.items.top)
{
Expand All @@ -184,11 +193,18 @@ namespace AppInstaller::YAML::Wrapper
{
// We've reached the end of the sequence
pop = true;
nestLevel--;
}
break;
}
case YAML_MAPPING_NODE:
{
if (stackItem.childOffset == 0)
{
// We've entered the mapping.
nestLevel++;
}

yaml_node_pair_t* child = stackItem.yamlNode->data.mapping.pairs.start + stackItem.childOffset++;
if (child < stackItem.yamlNode->data.mapping.pairs.top)
{
Expand All @@ -207,6 +223,7 @@ namespace AppInstaller::YAML::Wrapper
{
// We've reached the end of the mapping
pop = true;
nestLevel--;
}
break;
}
Expand All @@ -216,6 +233,8 @@ namespace AppInstaller::YAML::Wrapper
{
resultStack.pop();
}

THROW_HR_IF_MSG(APPINSTALLER_CLI_ERROR_YAML_DOC_BUILD_FAILED, nestLevel > YAML_DOCUMENT_NEST_LEVEL_LIMIT, "Too many layers of nested nodes.");
}

return result;
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