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[1.10>master] [MERGE chakra-core#5451 @paolosevMSFT] Ensure that GeneratorReturnExceptions are not handled by InterpreterStackFrame::DebugProcess
Merge pull request chakra-core#5451 from paolosevMSFT:user/paolosev/bug17418795 When running a generator function with the -debuglaunch flag the engine crashes with simple code like: ``` function* test() { try { yield 42; } catch (e) { } } var t = test(); t.next(); var v = t.return(); ``` The reason is that a special exception is thrown by JavascriptOperators::OP_ResumeYield() to carry the return value from a generator. When the generator has a try/catch, like in this case, this exception is caught and rethrown by InterpreterStackFrame::OP_TryCatch(), and after that it is caught and handled by JavascriptGenerator::CallGenerator(). But when we run with -debuglaunch the exception gets caught by InterpreterStackFrame::DebugProcess(), which does not rethrow it. Therefore the generator code does not have a chance to complete correctly and the process crashes because an invalid var is returned in place of a generator yielded object. As fix this PR adds a check for IsGeneratorReturnException() in InterpreterStackFrame::DebugProcess() to avoid skipping this exception.
2 parents 326847c + 9fdb174 commit b371ceb

4 files changed

Lines changed: 48 additions & 40 deletions

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‎lib/Runtime/Language/InterpreterStackFrame.cpp‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2363,8 +2363,9 @@ namespace Js
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if (exception)
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{
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bool skipException = false;
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if (exception != scriptContext->GetThreadContext()->GetPendingSOErrorObject()
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&& exception != scriptContext->GetThreadContext()->GetPendingOOMErrorObject())
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if (!exception->IsGeneratorReturnException() &&
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exception != scriptContext->GetThreadContext()->GetPendingSOErrorObject() &&
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exception != scriptContext->GetThreadContext()->GetPendingOOMErrorObject())
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{
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skipException = exception->IsDebuggerSkip();
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}

‎test/DebuggerCommon/generators.js‎

Lines changed: 19 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -124,12 +124,28 @@ g = gf4(); /**bp:
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stack();resume('step_into');
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stack();resume('step_into');
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stack();resume('step_into');
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stack();resume('step_out');
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stack();resume('step_out');
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**/
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g.next(1);
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g.return(2);
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function* gf5() {
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try {
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yield 32;
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} catch (e) {
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}
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}
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g = gf5(); /**bp:
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stack();resume('step_over');
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resume('step_over');
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stack();resume('step_into');
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stack();resume('step_out');
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stack();
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**/
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g.next();
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g.return(1);
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WScript.Echo("PASS");

‎test/DebuggerCommon/generators.js.dbg.baseline‎

Lines changed: 21 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -524,7 +524,7 @@
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{
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"callStack": [
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{
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"line": 132,
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"line": 129,
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"column": 0,
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"sourceText": "g.return(2)",
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"function": "Global code"
@@ -540,7 +540,7 @@
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"function": "gf4"
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},
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{
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"line": 132,
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"line": 129,
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"column": 0,
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"sourceText": "g.return(2)",
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"function": "Global code"
@@ -550,59 +550,45 @@
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{
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"callStack": [
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{
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"line": 77,
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"column": 4,
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"sourceText": "yield 1",
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"function": "gf3"
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},
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{
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"line": 82,
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"column": 4,
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"sourceText": "yield* gf3()",
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"function": "gf4"
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},
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{
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"line": 132,
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"line": 138,
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"column": 0,
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"sourceText": "g.return(2)",
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"sourceText": "g = gf5()",
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"function": "Global code"
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}
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]
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},
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{
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"callStack": [
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{
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"line": 78,
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"column": 4,
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"sourceText": "yield 2",
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"function": "gf3"
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},
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"line": 148,
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"column": 0,
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"sourceText": "g.return(1)",
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"function": "Global code"
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}
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]
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},
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{
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"callStack": [
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{
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"line": 82,
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"column": 4,
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"sourceText": "yield* gf3()",
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"function": "gf4"
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"line": 133,
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"column": 8,
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"sourceText": "yield 32",
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"function": "gf5"
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},
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{
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"line": 132,
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"line": 148,
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"column": 0,
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"sourceText": "g.return(2)",
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"sourceText": "g.return(1)",
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"function": "Global code"
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}
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]
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},
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{
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"callStack": [
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{
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"line": 82,
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"column": 4,
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"sourceText": "yield* gf3()",
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"function": "gf4"
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},
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{
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"line": 132,
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"line": 150,
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"column": 0,
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"sourceText": "g.return(2)",
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"sourceText": "WScript.Echo(\"PASS\")",
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"function": "Global code"
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}
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]

‎test/es6/generators-functionality.js‎

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Original file line numberDiff line numberDiff line change
@@ -949,6 +949,11 @@ var tests = [
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assert.areEqual({ value: 2, done: false }, g.return(100), "Return causes the finally block to execute");
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assert.throws(function () { g.next(); }, ExpectedException, "Second next call should throw from finally block");
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assert.areEqual({ value: undefined, done: true }, g.next(), "Method execution has finished");
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gf = function* () { try { throw new ExpectedException(); } catch (e) { throw e; } }
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g = gf();
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assert.throws(function () { g.next() }, ExpectedException, "First next call should rethrow exception");
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assert.areEqual({ value: 2, done: true }, g.return(2), "Return statement completes the function from try block");
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}
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},
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{

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