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Merge pull request #4717 from criemen/escapetree-temp-objects

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C++: Improve EscapesTree.qll analysis in the presence of temporary objects
This commit is contained in:
Jonas Jensen
2020-11-25 17:11:44 +01:00
committed by GitHub
parent aa45920f31 0b8403fc05
commit dcc048139e
10 changed files with 72 additions and 2 deletions
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11
cpp/ql/src/semmle/code/cpp/dataflow/EscapesTree.qll
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@@ -222,6 +222,15 @@ private predicate addressMayEscapeMutablyAt(Expr e) {
// If the address has been cast to an integral type, conservatively assume that it may eventually be cast back to a
// pointer to non-const type.
t instanceof IntegralType
or
// If we go through a temporary object step, we can take a reference to a temporary const pointer
// object, where the pointer doesn't point to a const value
exists(TemporaryObjectExpr temp, PointerType pt |
temp.getConversion() = e.(ReferenceToExpr) and
pt = temp.getType().stripTopLevelSpecifiers()
|
not pt.getBaseType().isConst()
)
)
}
@@ -249,7 +258,7 @@ private predicate addressFromVariableAccess(VariableAccess va, Expr e) {
// `e` could be a pointer that is converted to a reference as the final step,
// meaning that we pass a value that is two dereferences away from referring
// to `va`. This happens, for example, with `void std::vector::push_back(T&&
// value);` when called as `v.push_back(&x)`, for a static variable `x`. It
// value);` when called as `v.push_back(&x)`, for a variable `x`. It
// can also happen when taking a reference to a const pointer to a
// (potentially non-const) value.
exists(Expr pointerValue |

6
cpp/ql/test/library-tests/defuse/definition.expected
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@@ -1,5 +1,6 @@
| addressOf.cpp:23:9:23:9 | i | addressOf.cpp:24:22:24:30 | call to move |
| addressOf.cpp:23:9:23:9 | i | addressOf.cpp:25:25:25:26 | & ... |
| addressOf.cpp:23:9:23:9 | i | addressOf.cpp:26:31:26:32 | & ... |
| addressOf.cpp:31:23:31:23 | i | addressOf.cpp:32:18:32:19 | & ... |
| addressOf.cpp:31:23:31:23 | i | addressOf.cpp:34:18:34:33 | ... ? ... : ... |
| addressOf.cpp:31:23:31:23 | i | addressOf.cpp:35:18:35:23 | & ... |
@@ -77,6 +78,11 @@
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:46:11:46:11 | n |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:49:5:49:7 | ... ++ |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:53:22:53:22 | i |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:60:10:60:11 | 2 |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:61:34:61:35 | & ... |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:66:12:66:18 | 0 |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:74:10:74:11 | 2 |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:75:35:75:36 | & ... |
| test.cpp:4:7:4:7 | a | test.cpp:5:3:5:8 | ... = ... |
| test.cpp:4:7:4:7 | a | test.cpp:13:3:13:7 | ... = ... |
| test.cpp:4:7:4:7 | a | test.cpp:19:5:19:9 | ... = ... |

6
cpp/ql/test/library-tests/defuse/definitionUsePair.expected
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@@ -75,6 +75,12 @@
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:46:11:46:11 | n | pass_by_ref.cpp:53:22:53:22 | i |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:49:5:49:7 | ... ++ | pass_by_ref.cpp:53:22:53:22 | i |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:53:22:53:22 | i | pass_by_ref.cpp:54:10:54:10 | i |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:60:10:60:11 | 2 | pass_by_ref.cpp:61:35:61:35 | x |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:61:34:61:35 | & ... | pass_by_ref.cpp:62:10:62:10 | x |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:66:12:66:18 | 0 | pass_by_ref.cpp:67:34:67:34 | p |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:66:12:66:18 | 0 | pass_by_ref.cpp:68:10:68:10 | p |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:74:10:74:11 | 2 | pass_by_ref.cpp:75:36:75:36 | x |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:75:35:75:36 | & ... | pass_by_ref.cpp:76:10:76:10 | x |
| test.cpp:4:7:4:7 | a | test.cpp:5:3:5:8 | ... = ... | test.cpp:9:7:9:7 | a |
| test.cpp:4:7:4:7 | a | test.cpp:13:3:13:7 | ... = ... | test.cpp:14:7:14:7 | a |
| test.cpp:4:7:4:7 | a | test.cpp:13:3:13:7 | ... = ... | test.cpp:18:7:18:7 | a |

3
cpp/ql/test/library-tests/defuse/exprDefinition.expected
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@@ -17,6 +17,9 @@
| pass_by_ref.cpp:31:7:31:9 | arr | pass_by_ref.cpp:31:15:31:18 | {...} | pass_by_ref.cpp:31:15:31:18 | {...} |
| pass_by_ref.cpp:37:7:37:9 | arr | pass_by_ref.cpp:37:15:37:18 | {...} | pass_by_ref.cpp:37:15:37:18 | {...} |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:46:11:46:11 | n | pass_by_ref.cpp:46:11:46:11 | n |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:60:10:60:11 | 2 | pass_by_ref.cpp:60:10:60:11 | 2 |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:66:12:66:18 | 0 | pass_by_ref.cpp:66:12:66:18 | 0 |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:74:10:74:11 | 2 | pass_by_ref.cpp:74:10:74:11 | 2 |
| test.cpp:4:7:4:7 | a | test.cpp:5:3:5:8 | ... = ... | test.cpp:5:7:5:8 | a0 |
| test.cpp:4:7:4:7 | a | test.cpp:13:3:13:7 | ... = ... | test.cpp:13:7:13:7 | b |
| test.cpp:4:7:4:7 | a | test.cpp:19:5:19:9 | ... = ... | test.cpp:19:9:19:9 | 1 |

8
cpp/ql/test/library-tests/defuse/isAddressOfAccess.expected
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@@ -1,7 +1,7 @@
| addressOf.cpp:14:28:14:29 | d_ | non-const address |
| addressOf.cpp:24:32:24:32 | i | non-const address |
| addressOf.cpp:25:26:25:26 | i | non-const address |
| addressOf.cpp:26:32:26:32 | i | const address |
| addressOf.cpp:26:32:26:32 | i | non-const address |
| addressOf.cpp:32:19:32:19 | i | non-const address |
| addressOf.cpp:34:18:34:18 | i | |
| addressOf.cpp:34:23:34:23 | i | non-const address |
@@ -151,6 +151,12 @@
| pass_by_ref.cpp:49:5:49:5 | i | |
| pass_by_ref.cpp:53:22:53:22 | i | non-const address |
| pass_by_ref.cpp:54:10:54:10 | i | |
| pass_by_ref.cpp:61:35:61:35 | x | non-const address |
| pass_by_ref.cpp:62:10:62:10 | x | |
| pass_by_ref.cpp:67:34:67:34 | p | const address |
| pass_by_ref.cpp:68:10:68:10 | p | |
| pass_by_ref.cpp:75:36:75:36 | x | non-const address |
| pass_by_ref.cpp:76:10:76:10 | x | |
| test.cpp:5:3:5:3 | a | |
| test.cpp:5:7:5:8 | a0 | |
| test.cpp:6:3:6:3 | b | |

22
cpp/ql/test/library-tests/defuse/pass_by_ref.cpp
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@@ -53,3 +53,25 @@ int afterIf(int n) {
referenceParameter(i);
return i;
}
void constPointerReferenceParameter(int * const & pRef);
int temporaryObject() {
int x = 2;
constPointerReferenceParameter(&x);
return x;
}
int * noTemporaryObject() {
int *p = nullptr;
constPointerReferenceParameter(p);
return p;
}
void pointerRvalueReferenceParameter(int * && pRef);
int temporaryObject2() {
int x = 2;
pointerRvalueReferenceParameter(&x);
return x;
}

6
cpp/ql/test/library-tests/defuse/useOfVar.expected
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@@ -118,6 +118,12 @@
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:49:5:49:5 | i |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:53:22:53:22 | i |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:54:10:54:10 | i |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:61:35:61:35 | x |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:62:10:62:10 | x |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:67:34:67:34 | p |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:68:10:68:10 | p |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:75:36:75:36 | x |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:76:10:76:10 | x |
| test.cpp:3:16:3:17 | a0 | test.cpp:5:7:5:8 | a0 |
| test.cpp:3:24:3:25 | b0 | test.cpp:6:7:6:8 | b0 |
| test.cpp:3:32:3:33 | c0 | test.cpp:7:7:7:8 | c0 |

3
cpp/ql/test/library-tests/defuse/useOfVarActual.expected
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@@ -56,6 +56,9 @@
| pass_by_ref.cpp:45:17:45:17 | n | pass_by_ref.cpp:48:7:48:7 | n |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:49:5:49:5 | i |
| pass_by_ref.cpp:46:7:46:7 | i | pass_by_ref.cpp:54:10:54:10 | i |
| pass_by_ref.cpp:60:7:60:7 | x | pass_by_ref.cpp:62:10:62:10 | x |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:68:10:68:10 | p |
| pass_by_ref.cpp:74:7:74:7 | x | pass_by_ref.cpp:76:10:76:10 | x |
| test.cpp:3:16:3:17 | a0 | test.cpp:5:7:5:8 | a0 |
| test.cpp:3:24:3:25 | b0 | test.cpp:6:7:6:8 | b0 |
| test.cpp:3:32:3:33 | c0 | test.cpp:7:7:7:8 | c0 |

1
cpp/ql/test/library-tests/defuse/useUsePair.expected
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@@ -25,6 +25,7 @@
| pass_by_ref.cpp:21:7:21:8 | i2 | pass_by_ref.cpp:24:26:24:27 | i2 | pass_by_ref.cpp:27:39:27:40 | i2 |
| pass_by_ref.cpp:21:7:21:8 | i2 | pass_by_ref.cpp:25:27:25:28 | i2 | pass_by_ref.cpp:27:39:27:40 | i2 |
| pass_by_ref.cpp:45:17:45:17 | n | pass_by_ref.cpp:46:11:46:11 | n | pass_by_ref.cpp:48:7:48:7 | n |
| pass_by_ref.cpp:66:8:66:8 | p | pass_by_ref.cpp:67:34:67:34 | p | pass_by_ref.cpp:68:10:68:10 | p |
| test.cpp:4:7:4:7 | a | test.cpp:14:7:14:7 | a | test.cpp:18:7:18:7 | a |
| test.cpp:4:7:4:7 | a | test.cpp:14:7:14:7 | a | test.cpp:24:7:24:7 | a |
| test.cpp:4:7:4:7 | a | test.cpp:14:7:14:7 | a | test.cpp:28:11:28:11 | a |

8
cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/RegressionTests.cpp
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@@ -116,3 +116,11 @@ void negativeZero4(int val) {
if (val == 0) // GOOD [NO LONGER REPORTED]
;
}
void f(int *const &ref_to_ptr);
void testTempObject() {
int x = 0;
f(&x);
if (x > 0) {} // GOOD [NO LONGER REPORTED]
}