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C++: Make any non-overflowing arithmetic operation a barrier.

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This commit is contained in:
Mathias Vorreiter Pedersen
2021-06-21 14:05:34 +02:00
parent 18e5d3cce8
commit 238c483e5b
3 changed files with 9 additions and 17 deletions
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11
cpp/ql/src/Security/CWE/CWE-190/ArithmeticUncontrolled.ql
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@@ -36,7 +36,7 @@ predicate boundedDiv(Expr e, Expr left) { e = left }
/**
* An operand `e` of a remainder expression `rem` (i.e., `rem` is either a `RemExpr` or
* an `AssignRemExpr`) with left-hand side `left` and right-ahnd side `right` is bounded
* an `AssignRemExpr`) with left-hand side `left` and right-hand side `right` is bounded
* when `e` is `left` and `right` is upper bounded by some number that is less than the maximum integer
* allowed by the result type of `rem`.
*/
@@ -59,10 +59,15 @@ predicate boundedBitwiseAnd(Expr e, Expr andExpr, Expr operand1, Expr operand2)
}
/**
* Holds if `fc` is a part of the left operand of a binary operation that greatly reduces the range
* of possible values.
* Holds if `e` is an operand of an operation that greatly reduces the range of possible values.
*/
predicate bounded(Expr e) {
(
e instanceof UnaryArithmeticOperation or
e instanceof BinaryArithmeticOperation
) and
not convertedExprMightOverflow(e)
or
// For `%` and `&` we require that `e` is bounded by a value that is strictly smaller than the
// maximum possible value of the result type of the operation.
// For example, the function call `rand()` is considered bounded in the following program:

13
cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/uncontrolled/ArithmeticUncontrolled.expected
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@@ -19,11 +19,6 @@ edges
| test.c:99:14:99:19 | call to rand | test.c:100:5:100:5 | r |
| test.c:99:14:99:19 | call to rand | test.c:100:5:100:5 | r |
| test.c:99:14:99:19 | call to rand | test.c:100:5:100:5 | r |
| test.c:104:13:104:16 | call to rand | test.c:106:5:106:11 | r |
| test.c:104:13:104:16 | call to rand | test.c:106:5:106:11 | r |
| test.c:106:5:106:11 | r | test.c:110:18:110:18 | r |
| test.c:110:18:110:18 | r | test.c:111:3:111:3 | r |
| test.c:110:18:110:18 | r | test.c:111:3:111:3 | r |
| test.cpp:8:9:8:12 | Store | test.cpp:24:11:24:18 | call to get_rand |
| test.cpp:8:9:8:12 | call to rand | test.cpp:8:9:8:12 | Store |
| test.cpp:8:9:8:12 | call to rand | test.cpp:8:9:8:12 | Store |
@@ -67,13 +62,6 @@ nodes
| test.c:100:5:100:5 | r | semmle.label | r |
| test.c:100:5:100:5 | r | semmle.label | r |
| test.c:100:5:100:5 | r | semmle.label | r |
| test.c:104:13:104:16 | call to rand | semmle.label | call to rand |
| test.c:104:13:104:16 | call to rand | semmle.label | call to rand |
| test.c:106:5:106:11 | r | semmle.label | r |
| test.c:110:18:110:18 | r | semmle.label | r |
| test.c:111:3:111:3 | r | semmle.label | r |
| test.c:111:3:111:3 | r | semmle.label | r |
| test.c:111:3:111:3 | r | semmle.label | r |
| test.cpp:8:9:8:12 | Store | semmle.label | Store |
| test.cpp:8:9:8:12 | call to rand | semmle.label | call to rand |
| test.cpp:8:9:8:12 | call to rand | semmle.label | call to rand |
@@ -105,7 +93,6 @@ nodes
| test.c:45:5:45:5 | r | test.c:44:13:44:16 | call to rand | test.c:45:5:45:5 | r | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test.c:44:13:44:16 | call to rand | Uncontrolled value |
| test.c:77:9:77:9 | r | test.c:75:13:75:19 | ... ^ ... | test.c:77:9:77:9 | r | $@ flows to here and is used in arithmetic, potentially causing an underflow. | test.c:75:13:75:19 | ... ^ ... | Uncontrolled value |
| test.c:100:5:100:5 | r | test.c:99:14:99:19 | call to rand | test.c:100:5:100:5 | r | $@ flows to here and is used in arithmetic, potentially causing an underflow. | test.c:99:14:99:19 | call to rand | Uncontrolled value |
| test.c:111:3:111:3 | r | test.c:104:13:104:16 | call to rand | test.c:111:3:111:3 | r | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test.c:104:13:104:16 | call to rand | Uncontrolled value |
| test.cpp:25:7:25:7 | r | test.cpp:8:9:8:12 | call to rand | test.cpp:25:7:25:7 | r | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test.cpp:8:9:8:12 | call to rand | Uncontrolled value |
| test.cpp:31:7:31:7 | r | test.cpp:13:10:13:13 | call to rand | test.cpp:31:7:31:7 | r | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test.cpp:13:10:13:13 | call to rand | Uncontrolled value |
| test.cpp:37:7:37:7 | r | test.cpp:18:9:18:12 | call to rand | test.cpp:37:7:37:7 | r | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test.cpp:18:9:18:12 | call to rand | Uncontrolled value |

2
cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/uncontrolled/test.c
View File

@@ -108,5 +108,5 @@ void randomTester() {
}
void add_100(int r) {
r += 100; // GOOD [FALSE POSITIVE]
r += 100; // GOOD
}