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fix: prevent out-of-bounds read in tryBacktrackAddStarExportBinding #41

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Merged
anonrig merged 1 commit into from
Mar 11, 2026
Merged

fix: prevent out-of-bounds read in tryBacktrackAddStarExportBinding #41

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8 changes: 5 additions & 3 deletions src/parser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1475,11 +1475,13 @@ class CJSLexer {
}

void tryBacktrackAddStarExportBinding(const char* bPos) {
while (*bPos == ' ' && bPos > source)
if (bPos < source) return;
while (bPos > source && *bPos == ' ')
bPos--;
if (*bPos == '=') {
if (bPos <= source) return;
bPos--;
while (*bPos == ' ' && bPos > source)
while (bPos > source && *bPos == ' ')
bPos--;
const char* id_end = bPos;
bool identifierStart = false;
Expand All @@ -1494,7 +1496,7 @@ class CJSLexer {
if (starExportStack == STAR_EXPORT_STACK_END)
return;
starExportStack->id = std::string_view(bPos + 1, static_cast<size_t>(id_end - bPos));
while (*bPos == ' ' && bPos > source)
while (bPos > source && *bPos == ' ')
bPos--;
switch (*bPos) {
case 'r':
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34 changes: 34 additions & 0 deletions tests/real_world_tests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1272,6 +1272,40 @@ TEST(real_world_tests, line_numbers_reexports) {
ASSERT_EQ(result->re_exports[0].line, 2);
}

// Regression test for nodejs/node#62212:
// SIGSEGV when parsing a CJS bundle that starts with require() at position 0.
// tryBacktrackAddStarExportBinding was passed (source - 1) and dereferenced
// the pointer before checking it against the source boundary.
TEST(real_world_tests, require_at_start_of_input) {
// Minimal case: require() as the very first token triggers
// tryBacktrackAddStarExportBinding(startPos - 1) where startPos == source.
auto result = lexer::parse_commonjs("require('./foo')");
ASSERT_TRUE(result.has_value());

// Typical ncc/webpack bundle pattern that starts with require()
auto result2 = lexer::parse_commonjs(
"require('./sourcemap-register.js');"
"(()=>{var __webpack_modules__={"
"0:(module,exports,__webpack_require__)=>{"
"\"use strict\";"
"var _a=__webpack_require__(1);"
"exports.default=_a;"
"}"
"};"
"var __webpack_module_cache__={};"
"function __webpack_require__(id){"
"var c=__webpack_module_cache__[id];"
"if(c!==undefined)return c.exports;"
"var m=__webpack_module_cache__[id]={exports:{}};"
"__webpack_modules__[id](m,m.exports,__webpack_require__);"
"return m.exports;}"
"var __webpack_exports__=__webpack_require__(0);"
"module.exports=__webpack_exports__;"
"})();"
);
ASSERT_TRUE(result2.has_value());
}

TEST(real_world_tests, line_numbers_after_block_comment) {
auto result = lexer::parse_commonjs(
"/*\n"
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