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geoffw0geoffw0
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C++: Model operator new and operator new[].
1 parent ef68bd6 commit 259f714

3 files changed

Lines changed: 59 additions & 8 deletions

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‎cpp/ql/src/semmle/code/cpp/exprs/Expr.qll‎

Lines changed: 5 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,7 @@ import semmle.code.cpp.Element
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private import semmle.code.cpp.Enclosing
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private import semmle.code.cpp.internal.ResolveClass
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private import semmle.code.cpp.internal.AddressConstantExpression
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private import semmle.code.cpp.models.implementations.Allocation
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/**
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* A C/C++ expression.
@@ -804,8 +805,10 @@ class NewOrNewArrayExpr extends Expr, @any_new_expr {
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* call the constructor of `T` but will not allocate memory.
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*/
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Expr getPlacementPointer() {
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isStandardPlacementNewAllocator(this.getAllocator()) and
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result = this.getAllocatorCall().getArgument(1)
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result =
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this
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.getAllocatorCall()
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.getArgument(this.getAllocator().(OperatorNewAllocationFunction).getPlacementArgument())
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}
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}
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@@ -1194,12 +1197,6 @@ private predicate convparents(Expr child, int idx, Element parent) {
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)
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}
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1197-
private predicate isStandardPlacementNewAllocator(Function operatorNew) {
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operatorNew.getName().matches("operator new%") and
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operatorNew.getNumberOfParameters() = 2 and
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operatorNew.getParameter(1).getType() instanceof VoidPointerType
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}
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// Pulled out for performance. See QL-796.
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private predicate hasNoConversions(Expr e) { not e.hasConversion() }
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‎cpp/ql/src/semmle/code/cpp/models/implementations/Allocation.qll‎

Lines changed: 33 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -215,6 +215,39 @@ class SizelessAllocationFunction extends AllocationFunction {
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}
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}
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/**
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* An `operator new` or `operator new[]` function that may be associated with a `new` or
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* `new[]` expression. Note that `new` and `new[]` are not function calls, but these
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* functions may also be called directly.
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*/
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class OperatorNewAllocationFunction extends AllocationFunction {
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OperatorNewAllocationFunction() {
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exists(string name |
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hasGlobalOrStdName(name) and
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(
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// operator new(bytes, ...)
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name = "operator new" or
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// operator new[](bytes, ...)
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name = "operator new[]"
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)
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)
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}
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override int getSizeArg() { result = 0 }
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override predicate requiresDealloc() { not exists(getPlacementArgument()) }
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/**
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* Gets the position of the placement pointer if this is a placement
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* `operator new` function.
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*/
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int getPlacementArgument() {
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getNumberOfParameters() = 2 and
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getParameter(1).getType() instanceof VoidPointerType and
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result = 1
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}
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}
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/**
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* An allocation expression that is a function call, such as call to `malloc`.
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*/

‎cpp/ql/test/library-tests/allocators/allocators.expected‎

Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -47,15 +47,31 @@ deleteArrayExprs
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| allocators.cpp:82:3:82:49 | delete[] | PolymorphicBase | operator delete[](void *, unsigned long) -> void | 8 | 8 | sized |
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| allocators.cpp:83:3:83:23 | delete[] | int | operator delete[](void *, unsigned long) -> void | 4 | 4 | sized |
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allocationFunctions
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| allocators.cpp:7:7:7:18 | operator new | getSizeArg = 0, requiresDealloc |
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| allocators.cpp:8:7:8:20 | operator new[] | getSizeArg = 0, requiresDealloc |
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| allocators.cpp:9:7:9:18 | operator new | getSizeArg = 0, requiresDealloc |
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| allocators.cpp:10:7:10:20 | operator new[] | getSizeArg = 0, requiresDealloc |
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| allocators.cpp:121:7:121:18 | operator new | getSizeArg = 0 |
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| allocators.cpp:122:7:122:20 | operator new[] | getSizeArg = 0 |
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| allocators.cpp:123:7:123:18 | operator new | getSizeArg = 0, requiresDealloc |
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| allocators.cpp:124:7:124:20 | operator new[] | getSizeArg = 0, requiresDealloc |
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| file://:0:0:0:0 | operator new | getSizeArg = 0, requiresDealloc |
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| file://:0:0:0:0 | operator new | getSizeArg = 0, requiresDealloc |
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| file://:0:0:0:0 | operator new[] | getSizeArg = 0, requiresDealloc |
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| file://:0:0:0:0 | operator new[] | getSizeArg = 0, requiresDealloc |
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allocationExprs
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| allocators.cpp:49:3:49:9 | new | getSizeBytes = 4, requiresDealloc |
64+
| allocators.cpp:50:3:50:15 | call to operator new | getSizeExpr = <error expr>, getSizeMult = 1, requiresDealloc |
5265
| allocators.cpp:50:3:50:15 | new | getSizeBytes = 4, requiresDealloc |
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| allocators.cpp:51:3:51:11 | new | getSizeBytes = 4, requiresDealloc |
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| allocators.cpp:52:3:52:14 | new | getSizeBytes = 8, requiresDealloc |
68+
| allocators.cpp:53:3:53:27 | call to operator new | getSizeExpr = <error expr>, getSizeMult = 1, requiresDealloc |
5569
| allocators.cpp:53:3:53:27 | new | getSizeBytes = 8, requiresDealloc |
5670
| allocators.cpp:54:3:54:17 | new | getSizeBytes = 256, requiresDealloc |
71+
| allocators.cpp:55:3:55:25 | call to operator new | getSizeExpr = <error expr>, getSizeMult = 1, requiresDealloc |
5772
| allocators.cpp:55:3:55:25 | new | getSizeBytes = 256, requiresDealloc |
5873
| allocators.cpp:68:3:68:12 | new[] | getSizeExpr = n, getSizeMult = 4, requiresDealloc |
74+
| allocators.cpp:69:3:69:18 | call to operator new[] | getSizeExpr = <error expr>, getSizeMult = 1, requiresDealloc |
5975
| allocators.cpp:69:3:69:18 | new[] | getSizeExpr = n, getSizeMult = 4, requiresDealloc |
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| allocators.cpp:70:3:70:15 | new[] | getSizeExpr = n, getSizeMult = 8, requiresDealloc |
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| allocators.cpp:71:3:71:20 | new[] | getSizeExpr = n, getSizeMult = 256, requiresDealloc |
@@ -64,13 +80,18 @@ allocationExprs
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| allocators.cpp:108:3:108:19 | new[] | getSizeExpr = n, getSizeMult = 1, requiresDealloc |
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| allocators.cpp:109:3:109:35 | new | getSizeBytes = 128, requiresDealloc |
6682
| allocators.cpp:110:3:110:37 | new[] | getSizeBytes = 1280, requiresDealloc |
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| allocators.cpp:129:3:129:21 | call to operator new | getSizeExpr = <error expr>, getSizeMult = 1 |
6784
| allocators.cpp:129:3:129:21 | new | getSizeBytes = 4 |
85+
| allocators.cpp:132:3:132:17 | call to operator new[] | getSizeExpr = <error expr>, getSizeMult = 1 |
6886
| allocators.cpp:132:3:132:17 | new[] | getSizeBytes = 4 |
87+
| allocators.cpp:135:3:135:26 | call to operator new | getSizeExpr = <error expr>, getSizeMult = 1, requiresDealloc |
6988
| allocators.cpp:135:3:135:26 | new | getSizeBytes = 4, requiresDealloc |
89+
| allocators.cpp:136:3:136:26 | call to operator new[] | getSizeExpr = <error expr>, getSizeMult = 1, requiresDealloc |
7090
| allocators.cpp:136:3:136:26 | new[] | getSizeBytes = 8, requiresDealloc |
7191
| allocators.cpp:142:13:142:27 | new[] | getSizeExpr = x, getSizeMult = 10, requiresDealloc |
7292
| allocators.cpp:143:13:143:28 | new[] | getSizeBytes = 400, requiresDealloc |
7393
| allocators.cpp:144:13:144:31 | new[] | getSizeExpr = x, getSizeMult = 900, requiresDealloc |
94+
| allocators.cpp:149:8:149:19 | call to operator new | getSizeBytes = 4, getSizeExpr = sizeof(int), getSizeMult = 1, requiresDealloc |
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deallocationFunctions
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deallocationExprs
7697
| allocators.cpp:59:3:59:35 | delete | getFreedExpr = 0 |

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