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C++: Refactor CWE-497 for clarity and performance #547

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Merged
adityasharad merged 1 commit into from
Nov 26, 2018
Merged

C++: Refactor CWE-497 for clarity and performance #547

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20 changes: 12 additions & 8 deletions cpp/ql/src/Security/CWE/CWE-497/ExposedSystemData.ql
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Original file line number Diff line number Diff line change
Expand Up @@ -33,14 +33,7 @@ abstract class SystemData extends Element {
result = getAnExpr() or

// flow via global or member variable (conservative approximation)
exists(Variable var |
(
var.getAnAssignedValue() = getAnExprIndirect() or
var.getAnAccess() = getAnExprIndirect()
) and
result = var.getAnAccess() and
not var instanceof LocalScopeVariable
) or
result = getAnAffectedVar().getAnAccess() or

// flow via stack variable
definitionUsePair(_, getAnExprIndirect(), result) or
Expand All @@ -50,6 +43,17 @@ abstract class SystemData extends Element {
// flow from assigned value to assignment expression
result.(AssignExpr).getRValue() = getAnExprIndirect()
}

/** Gets a global or member variable that may be affected by this system
* data (conservative approximation).
*/
private Variable getAnAffectedVar() {
(
result.getAnAssignedValue() = this.getAnExprIndirect() or
result.getAnAccess() = this.getAnExprIndirect()
) and
not result instanceof LocalScopeVariable
}
}

/**
Expand Down