[DSLX:FE] Add nesting guard for Pattern production in the grammar as …

…well.
google · Jan 1, 2025 · 1cf4bf4 · 1cf4bf4
1 parent d2a163b
commit 1cf4bf4
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Showing 2 changed files with 13 additions and 0 deletions.
diff --git a/xls/dslx/frontend/parser.cc b/xls/dslx/frontend/parser.cc
@@ -1418,6 +1418,8 @@ absl::StatusOr<Expr*> Parser::ParseComparisonExpression(
 }
 
 absl::StatusOr<NameDefTree*> Parser::ParsePattern(Bindings& bindings) {
+  XLS_ASSIGN_OR_RETURN(ExpressionDepthGuard depth_guard, BumpExpressionDepth());
+
   XLS_ASSIGN_OR_RETURN(std::optional<Token> oparen,
                        TryPopToken(TokenKind::kOParen));
   if (oparen.has_value()) {

diff --git a/xls/dslx/frontend/parser_test.cc b/xls/dslx/frontend/parser_test.cc
@@ -3207,6 +3207,17 @@ TEST_F(ParserTest, UnreasonablyDeepTypeDefinition) {
                                HasSubstr("Extremely deep nesting detected")));
 }
 
+// As above but guards the pattern-match production in the grammar.
+TEST_F(ParserTest, UnreasonablyDeepPatternMatch) {
+  constexpr std::string_view kProgram = R"(fn f(x: u32) { match x {
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((()";
+  Scanner s{file_table_, Fileno(0), std::string(kProgram)};
+  Parser parser{"test", &s};
+  absl::StatusOr<std::unique_ptr<Module>> module = parser.ParseModule();
+  EXPECT_THAT(module, StatusIs(absl::StatusCode::kInvalidArgument,
+                               HasSubstr("Extremely deep nesting detected")));
+}
+
 TEST_F(ParserTest, NonTypeDefinitionBeforeArrayLiteralColon) {
   constexpr std::string_view kProgram = "const A=4[5]:[";
   Scanner s{file_table_, Fileno(0), std::string(kProgram)};