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C#: Variable capture follow-up #15796

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Merged
hvitved merged 2 commits into from
Mar 5, 2024
Merged

C#: Variable capture follow-up #15796

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357638b
C#: Update variable capture test
hvitved Mar 4, 2024
a92e394
C#: Variable capture follow-up
hvitved Mar 4, 2024
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35 changes: 21 additions & 14 deletions csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -148,7 +148,7 @@ abstract private class LocalFunctionCreationNode extends NodeImpl, TLocalFunctio
LocalFunction getFunction() { result = function }

ExprNode getAnAccess(boolean inSameCallable) {
result.getExpr().(LocalFunctionAccess).getTarget() = this.getFunction() and
isLocalFunctionCallReceiver(_, result.getExpr(), this.getFunction()) and
if result.getEnclosingCallable() = this.getEnclosingCallable()
then inSameCallable = true
else inSameCallable = false
Expand Down Expand Up @@ -399,7 +399,11 @@ module VariableCapture {

predicate hasBody(Callable body) { body = c }

predicate hasAliasedAccess(Expr f) { closureFlowStep+(this, f) and not closureFlowStep(f, _) }
predicate hasAliasedAccess(Expr f) {
closureFlowStep+(this, f) and not closureFlowStep(f, _)
or
isLocalFunctionCallReceiver(_, f.getAstNode(), c)
}
}

class Callable extends Cs::Callable {
Expand Down Expand Up @@ -881,7 +885,7 @@ module LocalFlow {
exists(SsaImpl::getAReadAtNode(def, node2.(ExprNode).getControlFlowNode()))
)
or
delegateCreationStep(node1, node2)
node2 = node1.(LocalFunctionCreationNode).getAnAccess(true)
or
node1 =
unique(FlowSummaryNode n1 |
Expand Down Expand Up @@ -2549,9 +2553,10 @@ class DataFlowType extends TDataFlowType {
* creations associated with the same type.
*/
ControlFlowElement getADelegateCreation() {
exists(Callable callable |
lambdaCreationExpr(result, callable) and
this = TDelegateDataFlowType(callable)
exists(Callable callable | this = TDelegateDataFlowType(callable) |
lambdaCreationExpr(result, callable)
or
isLocalFunctionCallReceiver(_, result, callable)
)
}

Expand All @@ -2566,12 +2571,7 @@ class DataFlowType extends TDataFlowType {
DataFlowType getNodeType(Node n) {
result = n.(NodeImpl).getDataFlowType() and
not lambdaCreation(n, _, _) and
not delegateCreationStep(_, n)
or
exists(Node arg |
delegateCreationStep(arg, n) and
result = getNodeType(arg)
)
not isLocalFunctionCallReceiver(_, n.asExpr(), _)
or
[
n.asExpr().(ControlFlowElement),
Expand Down Expand Up @@ -2896,7 +2896,7 @@ private predicate lambdaCreationExpr(ControlFlowElement creation, Callable c) {
c =
[
creation.(AnonymousFunctionExpr),
creation.(CallableAccess).getTarget().getUnboundDeclaration(),
creation.(DelegateCreation).getArgument().(CallableAccess).getTarget().getUnboundDeclaration(),
creation.(AddressOfExpr).getOperand().(CallableAccess).getTarget().getUnboundDeclaration(),
creation.(LocalFunctionStmt).getLocalFunction()
]
Expand All @@ -2910,6 +2910,13 @@ predicate lambdaCreation(Node creation, LambdaCallKind kind, DataFlowCallable c)
exists(kind)
}

private predicate isLocalFunctionCallReceiver(
LocalFunctionCall call, LocalFunctionAccess receiver, LocalFunction f
) {
receiver.getParent() = call and
f = receiver.getTarget().getUnboundDeclaration()
}

private class LambdaConfiguration extends ControlFlowReachabilityConfiguration {
LambdaConfiguration() { this = "LambdaConfiguration" }

Expand All @@ -2926,7 +2933,7 @@ private class LambdaConfiguration extends ControlFlowReachabilityConfiguration {
scope = e2 and
isSuccessor = true
or
e1.(LocalFunctionAccess).getParent() = e2.(LocalFunctionCall) and
isLocalFunctionCallReceiver(e2, e1, _) and
exactScope = false and
scope = e2 and
isSuccessor = true
Expand Down
4 changes: 3 additions & 1 deletion csharp/ql/test/library-tests/dataflow/global/Capture.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -327,9 +327,11 @@ void M12()
{
var x = "taint source";

void CapturedLocalFunction() => Check(x); // missing flow from line 328
void CapturedLocalFunction() => Check(x);

void CapturingLocalFunction() => CapturedLocalFunction();

CapturingLocalFunction();
}

void M13()
Expand Down
2 changes: 1 addition & 1 deletion csharp/ql/test/library-tests/dataflow/global/DataFlow.expected
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Expand Up @@ -27,7 +27,7 @@
| Capture.cs:312:15:312:15 | access to local variable x |
| Capture.cs:319:19:319:19 | access to local variable x |
| Capture.cs:330:47:330:47 | access to local variable x |
| Capture.cs:339:45:339:45 | access to local variable x |
| Capture.cs:341:45:341:45 | access to local variable x |
| GlobalDataFlow.cs:19:15:19:29 | access to field SinkField0 |
| GlobalDataFlow.cs:27:15:27:32 | access to property SinkProperty0 |
| GlobalDataFlow.cs:45:50:45:59 | access to parameter sinkParam2 |
Expand Down
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