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core: enforce recursion depth limits when parsing function parameters and arguments #1340

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core: enforce recursion depth limits when parsing function parameters and arguments #1340

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15 changes: 9 additions & 6 deletions core/parser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -216,8 +216,11 @@ class Parser {
*/
ArgParams parseParams(const std::string &element_kind, bool &got_comma, Fodder &close_fodder, unsigned current_depth)
{
if (current_depth >= MAX_PARSER_DEPTH) {
throw StaticError(peek().location, "Exceeded maximum parse depth limit.");
}
ArgParams params;
Token paren_r = parseArgs(params, element_kind, got_comma, current_depth);
Token paren_r = parseArgs(params, element_kind, got_comma, current_depth + 1);

// Check they're all identifiers
// parseArgs returns f(x) with x as an expression. Convert it here.
Expand Down Expand Up @@ -259,7 +262,7 @@ class Parser {
if (peek().kind == Token::PAREN_L) {
Token paren_l = pop();
fodder_l = paren_l.fodder;
params = parseParams("function parameter", trailing_comma, fodder_r, current_depth);
params = parseParams("function parameter", trailing_comma, fodder_r, current_depth + 1);
is_function = true;
}
Token eq = popExpect(Token::OPERATOR, "=");
Expand Down Expand Up @@ -428,7 +431,7 @@ class Parser {
if (peek().kind == Token::PAREN_L) {
Token paren_l = pop();
fodder_l = paren_l.fodder;
params = parseParams("method parameter", meth_comma, fodder_r, current_depth);
params = parseParams("method parameter", meth_comma, fodder_r, current_depth + 1);
is_method = true;
}

Expand Down Expand Up @@ -519,7 +522,7 @@ class Parser {
Token paren_l = pop();
paren_l_fodder = paren_l.fodder;
is_method = true;
params = parseParams("function parameter", func_comma, paren_r_fodder, current_depth);
params = parseParams("function parameter", func_comma, paren_r_fodder, current_depth + 1);
}
Token eq = popExpect(Token::OPERATOR, "=");
AST *body = parse(MAX_PRECEDENCE, current_depth + 1);
Expand Down Expand Up @@ -879,7 +882,7 @@ class Parser {
std::vector<AST *> params_asts;
bool got_comma;
Fodder paren_r_fodder;
ArgParams params = parseParams("function parameter", got_comma, paren_r_fodder, current_depth);
ArgParams params = parseParams("function parameter", got_comma, paren_r_fodder, current_depth + 1);
AST *body = parse(MAX_PRECEDENCE, current_depth + 1);
return alloc->make<Function>(span(begin, body),
begin.fodder,
Expand Down Expand Up @@ -1129,7 +1132,7 @@ class Parser {
case Token::PAREN_L: {
ArgParams args;
bool got_comma;
Token end = parseArgs(args, "function argument", got_comma, current_depth);
Token end = parseArgs(args, "function argument", got_comma, current_depth + 1);
bool got_named = false;
for (const auto& arg : args) {
if (arg.id != nullptr) {
Expand Down
28 changes: 28 additions & 0 deletions core/parser_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -343,5 +343,33 @@ TEST(Parser, TestInvalidOverride)
testParseError("a{b c}", R"(test:1:5: expected token OPERATOR but got (IDENTIFIER, "c"))");
}

TEST(Parser, TestMaxDepthLimit)
{
// Test that deeply nested bracket expressions fail gracefully with depth limit error.
std::string deep_brackets = std::string(1000, '[') + "1" + std::string(1000, ']');
testParseError(deep_brackets.c_str(), "test:1:501: Exceeded maximum parse depth limit.");

// Test that deeply nested parens fail gracefully with depth limit error.
std::string deep_parens = std::string(1000, '(') + "1" + std::string(1000, ')');
testParseError(deep_parens.c_str(), "test:1:501: Exceeded maximum parse depth limit.");

// Test that deeply nested unary chains fail gracefully.
std::string deep_unary = std::string(1000, '!') + "true";
testParseError(deep_unary.c_str(), "test:1:501: Exceeded maximum parse depth limit.");

// Test that flat chained operations (binary +, indexing) parse fine without false positive depth errors.
std::string flat_binary = "1";
for (int i = 0; i < 1000; ++i) {
flat_binary += " + 1";
}
testParse(flat_binary.c_str());

std::string flat_index = "x";
for (int i = 0; i < 1000; ++i) {
flat_index += "[0]";
}
testParse(flat_index.c_str());
}

} // namespace
} // namespace jsonnet::internal
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