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Jul 11, 2025
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C++: Better dataflow for function objects #20023

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6736dd4
C++: Add some tests with missing flow through function objects.
MathiasVP Jul 11, 2025
11cba94
C++: Add a missing predicate on 'UninitializedInstruction' that we wi…
MathiasVP Jul 10, 2025
663c3e7
C++: Sync identical files.
MathiasVP Jul 10, 2025
b53c354
C++: Add lambda dispatch for functors.
MathiasVP Jul 10, 2025
df241ad
C++: Fix lambda creation for objects with no constructor.
MathiasVP Jul 10, 2025
6d0c8c6
C++: Work around an extractor bug.
MathiasVP Jul 10, 2025
4f538a2
C++: Accept taint test changes.
MathiasVP Jul 10, 2025
053a749
C++: Add change note.
MathiasVP Jul 11, 2025
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C++: Add lambda dispatch for functors.
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@MathiasVP
MathiasVP committed Jul 11, 2025
commit b53c3547d0880c0963bc4f9b7d90f198cef69406
64 changes: 59 additions & 5 deletions cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowPrivate.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -1382,16 +1382,63 @@ predicate neverSkipInPathGraph(Node n) {
exists(n.asIndirectDefinition())
}

class LambdaCallKind = Unit;
private newtype TLambdaCallKind =
TFunctionPointer() or
TFunctor()

class LambdaCallKind extends TLambdaCallKind {
predicate isFunctionPointer() { this = TFunctionPointer() }

predicate isFunctor() { this = TFunctor() }

string toString() {
this.isFunctionPointer() and
result = "Function pointer kind"
or
this.isFunctor() and
result = "Functor kind"
}
}

private class ConstructorCallInstruction extends CallInstruction {
Cpp::Class constructedType;

ConstructorCallInstruction() {
this.getStaticCallTarget().(Cpp::Constructor).getDeclaringType() = constructedType
}

Cpp::Class getConstructedType() { result = constructedType }
}

private class OperatorCall extends Cpp::MemberFunction {
OperatorCall() { this.hasName("operator()") }
}

private predicate isFunctorCreationWithConstructor(Node creation, OperatorCall operator) {
exists(DataFlowCall constructorCall, IndirectionPosition pos |
// A construction of an object with a constructor. In this case we use
// the post-update node of the qualifier
pos.getArgumentIndex() = -1 and
isArgumentNode(creation.(PostUpdateNode).getPreUpdateNode(), constructorCall, pos) and
operator.getDeclaringType() =
constructorCall.asCallInstruction().(ConstructorCallInstruction).getConstructedType()
)
}

/** Holds if `creation` is an expression that creates a lambda of kind `kind` for `c`. */
predicate lambdaCreation(Node creation, LambdaCallKind kind, DataFlowCallable c) {
creation.asInstruction().(FunctionAddressInstruction).getFunctionSymbol() = c.asSourceCallable() and
exists(kind)
kind.isFunctionPointer() and
creation.asInstruction().(FunctionAddressInstruction).getFunctionSymbol() = c.asSourceCallable()
or
kind.isFunctor() and
exists(OperatorCall operator | operator = c.asSourceCallable() |
isFunctorCreationWithConstructor(creation, operator)
)
}

/** Holds if `call` is a lambda call of kind `kind` where `receiver` is the lambda expression. */
predicate lambdaCall(DataFlowCall call, LambdaCallKind kind, Node receiver) {
kind.isFunctionPointer() and
(
call.(SummaryCall).getReceiver() = receiver.(FlowSummaryNode).getSummaryNode()
or
Expand All @@ -1400,8 +1447,15 @@ predicate lambdaCall(DataFlowCall call, LambdaCallKind kind, Node receiver) {
// has a result for `getStaticCallTarget`.
not exists(call.getStaticCallTarget()) and
call.asCallInstruction().getCallTargetOperand() = receiver.asOperand()
) and
exists(kind)
)
or
kind.isFunctor() and
(
call.(SummaryCall).getReceiver() = receiver.(FlowSummaryNode).getSummaryNode()
or
not exists(call.getStaticCallTarget()) and
call.asCallInstruction().getThisArgumentOperand() = receiver.asOperand()
)
}

/** Extra data-flow steps needed for lambda flow analysis. */
Expand Down
52 changes: 38 additions & 14 deletions cpp/ql/test/library-tests/dataflow/external-models/flow.expected
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Original file line number Diff line number Diff line change
Expand Up @@ -21,13 +21,14 @@ models
| 20 | Summary: ; ; false; CreateRemoteThreadEx; ; ; Argument[@4]; Argument[3].Parameter[@0]; value; manual |
| 21 | Summary: ; ; false; CreateThread; ; ; Argument[@3]; Argument[2].Parameter[@0]; value; manual |
| 22 | Summary: ; ; false; ReadFileEx; ; ; Argument[*3].Field[@hEvent]; Argument[4].Parameter[*2].Field[@hEvent]; value; manual |
| 23 | Summary: ; ; false; pthread_create; ; ; Argument[@3]; Argument[2].Parameter[@0]; value; manual |
| 24 | Summary: ; ; false; ymlStepGenerated; ; ; Argument[0]; ReturnValue; taint; df-generated |
| 25 | Summary: ; ; false; ymlStepManual; ; ; Argument[0]; ReturnValue; taint; manual |
| 26 | Summary: ; ; false; ymlStepManual_with_body; ; ; Argument[0]; ReturnValue; taint; manual |
| 27 | Summary: boost::asio; ; false; buffer; ; ; Argument[*0]; ReturnValue; taint; manual |
| 23 | Summary: ; ; false; callWithArgument; ; ; Argument[1]; Argument[0].Parameter[0]; value; manual |
| 24 | Summary: ; ; false; pthread_create; ; ; Argument[@3]; Argument[2].Parameter[@0]; value; manual |
| 25 | Summary: ; ; false; ymlStepGenerated; ; ; Argument[0]; ReturnValue; taint; df-generated |
| 26 | Summary: ; ; false; ymlStepManual; ; ; Argument[0]; ReturnValue; taint; manual |
| 27 | Summary: ; ; false; ymlStepManual_with_body; ; ; Argument[0]; ReturnValue; taint; manual |
| 28 | Summary: boost::asio; ; false; buffer; ; ; Argument[*0]; ReturnValue; taint; manual |
edges
| asio_streams.cpp:56:18:56:23 | [summary param] *0 in buffer | asio_streams.cpp:56:18:56:23 | [summary] to write: ReturnValue in buffer | provenance | MaD:27 |
| asio_streams.cpp:56:18:56:23 | [summary param] *0 in buffer | asio_streams.cpp:56:18:56:23 | [summary] to write: ReturnValue in buffer | provenance | MaD:28 |
| asio_streams.cpp:87:34:87:44 | read_until output argument | asio_streams.cpp:91:7:91:17 | recv_buffer | provenance | Src:MaD:17 |
| asio_streams.cpp:87:34:87:44 | read_until output argument | asio_streams.cpp:93:29:93:39 | *recv_buffer | provenance | Src:MaD:17 Sink:MaD:2 |
| asio_streams.cpp:97:37:97:44 | call to source | asio_streams.cpp:98:7:98:14 | send_str | provenance | TaintFunction |
Expand All @@ -36,10 +37,10 @@ edges
| asio_streams.cpp:100:44:100:62 | call to buffer | asio_streams.cpp:101:7:101:17 | send_buffer | provenance | |
| asio_streams.cpp:100:44:100:62 | call to buffer | asio_streams.cpp:103:29:103:39 | *send_buffer | provenance | Sink:MaD:2 |
| asio_streams.cpp:100:64:100:71 | *send_str | asio_streams.cpp:56:18:56:23 | [summary param] *0 in buffer | provenance | |
| asio_streams.cpp:100:64:100:71 | *send_str | asio_streams.cpp:100:44:100:62 | call to buffer | provenance | MaD:27 |
| test.cpp:4:5:4:17 | [summary param] 0 in ymlStepManual | test.cpp:4:5:4:17 | [summary] to write: ReturnValue in ymlStepManual | provenance | MaD:25 |
| test.cpp:5:5:5:20 | [summary param] 0 in ymlStepGenerated | test.cpp:5:5:5:20 | [summary] to write: ReturnValue in ymlStepGenerated | provenance | MaD:24 |
| test.cpp:6:5:6:27 | [summary param] 0 in ymlStepManual_with_body | test.cpp:6:5:6:27 | [summary] to write: ReturnValue in ymlStepManual_with_body | provenance | MaD:26 |
| asio_streams.cpp:100:64:100:71 | *send_str | asio_streams.cpp:100:44:100:62 | call to buffer | provenance | MaD:28 |
| test.cpp:4:5:4:17 | [summary param] 0 in ymlStepManual | test.cpp:4:5:4:17 | [summary] to write: ReturnValue in ymlStepManual | provenance | MaD:26 |
| test.cpp:5:5:5:20 | [summary param] 0 in ymlStepGenerated | test.cpp:5:5:5:20 | [summary] to write: ReturnValue in ymlStepGenerated | provenance | MaD:25 |
| test.cpp:6:5:6:27 | [summary param] 0 in ymlStepManual_with_body | test.cpp:6:5:6:27 | [summary] to write: ReturnValue in ymlStepManual_with_body | provenance | MaD:27 |
| test.cpp:7:47:7:52 | value2 | test.cpp:7:64:7:69 | value2 | provenance | |
| test.cpp:7:64:7:69 | value2 | test.cpp:7:5:7:30 | *ymlStepGenerated_with_body | provenance | |
| test.cpp:10:10:10:18 | call to ymlSource | test.cpp:10:10:10:18 | call to ymlSource | provenance | Src:MaD:16 |
Expand All @@ -51,28 +52,39 @@ edges
| test.cpp:17:10:17:22 | call to ymlStepManual | test.cpp:17:10:17:22 | call to ymlStepManual | provenance | |
| test.cpp:17:10:17:22 | call to ymlStepManual | test.cpp:18:10:18:10 | y | provenance | Sink:MaD:1 |
| test.cpp:17:24:17:24 | x | test.cpp:4:5:4:17 | [summary param] 0 in ymlStepManual | provenance | |
| test.cpp:17:24:17:24 | x | test.cpp:17:10:17:22 | call to ymlStepManual | provenance | MaD:25 |
| test.cpp:17:24:17:24 | x | test.cpp:17:10:17:22 | call to ymlStepManual | provenance | MaD:26 |
| test.cpp:21:10:21:25 | call to ymlStepGenerated | test.cpp:21:10:21:25 | call to ymlStepGenerated | provenance | |
| test.cpp:21:10:21:25 | call to ymlStepGenerated | test.cpp:22:10:22:10 | z | provenance | Sink:MaD:1 |
| test.cpp:21:27:21:27 | x | test.cpp:5:5:5:20 | [summary param] 0 in ymlStepGenerated | provenance | |
| test.cpp:21:27:21:27 | x | test.cpp:21:10:21:25 | call to ymlStepGenerated | provenance | MaD:24 |
| test.cpp:21:27:21:27 | x | test.cpp:21:10:21:25 | call to ymlStepGenerated | provenance | MaD:25 |
| test.cpp:25:11:25:33 | call to ymlStepManual_with_body | test.cpp:25:11:25:33 | call to ymlStepManual_with_body | provenance | |
| test.cpp:25:11:25:33 | call to ymlStepManual_with_body | test.cpp:26:10:26:11 | y2 | provenance | Sink:MaD:1 |
| test.cpp:25:35:25:35 | x | test.cpp:6:5:6:27 | [summary param] 0 in ymlStepManual_with_body | provenance | |
| test.cpp:25:35:25:35 | x | test.cpp:25:11:25:33 | call to ymlStepManual_with_body | provenance | MaD:26 |
| test.cpp:25:35:25:35 | x | test.cpp:25:11:25:33 | call to ymlStepManual_with_body | provenance | MaD:27 |
| test.cpp:32:11:32:36 | call to ymlStepGenerated_with_body | test.cpp:32:11:32:36 | call to ymlStepGenerated_with_body | provenance | |
| test.cpp:32:11:32:36 | call to ymlStepGenerated_with_body | test.cpp:33:10:33:11 | z2 | provenance | Sink:MaD:1 |
| test.cpp:32:41:32:41 | x | test.cpp:7:47:7:52 | value2 | provenance | |
| test.cpp:32:41:32:41 | x | test.cpp:32:11:32:36 | call to ymlStepGenerated_with_body | provenance | |
| test.cpp:46:30:46:32 | *arg [x] | test.cpp:47:12:47:19 | *arg [x] | provenance | |
| test.cpp:47:12:47:19 | *arg [x] | test.cpp:48:13:48:13 | *s [x] | provenance | |
| test.cpp:48:13:48:13 | *s [x] | test.cpp:48:16:48:16 | x | provenance | Sink:MaD:1 |
| test.cpp:52:5:52:18 | [summary param] *3 in pthread_create [x] | test.cpp:52:5:52:18 | [summary] to write: Argument[2].Parameter[*0] in pthread_create [x] | provenance | MaD:23 |
| test.cpp:52:5:52:18 | [summary param] *3 in pthread_create [x] | test.cpp:52:5:52:18 | [summary] to write: Argument[2].Parameter[*0] in pthread_create [x] | provenance | MaD:24 |
| test.cpp:52:5:52:18 | [summary] to write: Argument[2].Parameter[*0] in pthread_create [x] | test.cpp:46:30:46:32 | *arg [x] | provenance | |
| test.cpp:56:2:56:2 | *s [post update] [x] | test.cpp:59:55:59:64 | *& ... [x] | provenance | |
| test.cpp:56:2:56:18 | ... = ... | test.cpp:56:2:56:2 | *s [post update] [x] | provenance | |
| test.cpp:56:8:56:16 | call to ymlSource | test.cpp:56:2:56:18 | ... = ... | provenance | Src:MaD:16 |
| test.cpp:59:55:59:64 | *& ... [x] | test.cpp:52:5:52:18 | [summary param] *3 in pthread_create [x] | provenance | |
| test.cpp:63:6:63:21 | [summary param] 1 in callWithArgument | test.cpp:63:6:63:21 | [summary] to write: Argument[0].Parameter[0] in callWithArgument | provenance | MaD:23 |
| test.cpp:63:6:63:21 | [summary param] 1 in callWithArgument | test.cpp:63:6:63:21 | [summary] to write: Argument[0].Parameter[0] in callWithArgument | provenance | MaD:23 |
| test.cpp:63:6:63:21 | [summary] to write: Argument[0].Parameter[0] in callWithArgument | test.cpp:68:22:68:22 | y | provenance | |
| test.cpp:63:6:63:21 | [summary] to write: Argument[0].Parameter[0] in callWithArgument | test.cpp:82:22:82:22 | y | provenance | |
| test.cpp:68:22:68:22 | y | test.cpp:69:11:69:11 | y | provenance | Sink:MaD:1 |
| test.cpp:82:22:82:22 | y | test.cpp:83:11:83:11 | y | provenance | Sink:MaD:1 |
| test.cpp:94:10:94:18 | call to ymlSource | test.cpp:94:10:94:18 | call to ymlSource | provenance | Src:MaD:16 |
| test.cpp:94:10:94:18 | call to ymlSource | test.cpp:97:26:97:26 | x | provenance | |
| test.cpp:94:10:94:18 | call to ymlSource | test.cpp:103:63:103:63 | x | provenance | |
| test.cpp:97:26:97:26 | x | test.cpp:63:6:63:21 | [summary param] 1 in callWithArgument | provenance | |
| test.cpp:103:63:103:63 | x | test.cpp:63:6:63:21 | [summary param] 1 in callWithArgument | provenance | |
| windows.cpp:17:8:17:25 | [summary param] *0 in CommandLineToArgvA | windows.cpp:17:8:17:25 | [summary] to write: ReturnValue[**] in CommandLineToArgvA | provenance | MaD:18 |
| windows.cpp:22:15:22:29 | *call to GetCommandLineA | windows.cpp:22:15:22:29 | *call to GetCommandLineA | provenance | Src:MaD:3 |
| windows.cpp:22:15:22:29 | *call to GetCommandLineA | windows.cpp:24:8:24:11 | * ... | provenance | |
Expand Down Expand Up @@ -209,6 +221,18 @@ nodes
| test.cpp:56:2:56:18 | ... = ... | semmle.label | ... = ... |
| test.cpp:56:8:56:16 | call to ymlSource | semmle.label | call to ymlSource |
| test.cpp:59:55:59:64 | *& ... [x] | semmle.label | *& ... [x] |
| test.cpp:63:6:63:21 | [summary param] 1 in callWithArgument | semmle.label | [summary param] 1 in callWithArgument |
| test.cpp:63:6:63:21 | [summary param] 1 in callWithArgument | semmle.label | [summary param] 1 in callWithArgument |
| test.cpp:63:6:63:21 | [summary] to write: Argument[0].Parameter[0] in callWithArgument | semmle.label | [summary] to write: Argument[0].Parameter[0] in callWithArgument |
| test.cpp:63:6:63:21 | [summary] to write: Argument[0].Parameter[0] in callWithArgument | semmle.label | [summary] to write: Argument[0].Parameter[0] in callWithArgument |
| test.cpp:68:22:68:22 | y | semmle.label | y |
| test.cpp:69:11:69:11 | y | semmle.label | y |
| test.cpp:82:22:82:22 | y | semmle.label | y |
| test.cpp:83:11:83:11 | y | semmle.label | y |
| test.cpp:94:10:94:18 | call to ymlSource | semmle.label | call to ymlSource |
| test.cpp:94:10:94:18 | call to ymlSource | semmle.label | call to ymlSource |
| test.cpp:97:26:97:26 | x | semmle.label | x |
| test.cpp:103:63:103:63 | x | semmle.label | x |
| windows.cpp:17:8:17:25 | [summary param] *0 in CommandLineToArgvA | semmle.label | [summary param] *0 in CommandLineToArgvA |
| windows.cpp:17:8:17:25 | [summary] to write: ReturnValue[**] in CommandLineToArgvA | semmle.label | [summary] to write: ReturnValue[**] in CommandLineToArgvA |
| windows.cpp:22:15:22:29 | *call to GetCommandLineA | semmle.label | *call to GetCommandLineA |
Expand Down
4 changes: 2 additions & 2 deletions cpp/ql/test/library-tests/dataflow/external-models/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,7 @@ struct StructWithOperatorCall_has_constructor {
StructWithOperatorCall_has_constructor();

void operator()(int y) {
ymlSink(y); // $ MISSING: ir
ymlSink(y); // $ ir
}
};

Expand All @@ -80,7 +80,7 @@ struct StructWithOperatorCall_has_constructor_2 {
StructWithOperatorCall_has_constructor_2();

void operator()(int y) {
ymlSink(y); // $ MISSING: ir
ymlSink(y); // $ ir
}
};

Expand Down
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