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Python: Add read step for unpacking assignment

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This commit is contained in:
Rasmus Lerchedahl Petersen
2020-11-30 15:30:14 +01:00
parent f345e55951
commit 289b9e62f9
3 changed files with 36 additions and 1 deletions
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23
python/ql/src/semmle/python/dataflow/new/internal/DataFlowPrivate.qll
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@@ -976,6 +976,8 @@ predicate kwOverflowStoreStep(CfgNode nodeFrom, DictionaryElementContent c, Node
predicate readStep(Node nodeFrom, Content c, Node nodeTo) {
subscriptReadStep(nodeFrom, c, nodeTo)
or
unpackingAssignmentReadStep(nodeFrom, c, nodeTo)
or
popReadStep(nodeFrom, c, nodeTo)
or
comprehensionReadStep(nodeFrom, c, nodeTo)
@@ -1008,6 +1010,27 @@ predicate subscriptReadStep(CfgNode nodeFrom, Content c, CfgNode nodeTo) {
)
}
/** Data flows from an iterable to an assigned variable. */
predicate unpackingAssignmentReadStep(CfgNode nodeFrom, Content c, EssaNode nodeTo) {
// iterable unpacking
// `a, b = iterable`
// nodeFrom is `iterable`, cfg node
// nodeTo is `a` (or `b`), essa var
// c is compatible with `a`s (or `b`s) index
exists(Assign assign, int index, SequenceNode target |
target.getNode() = assign.getATarget() and
nodeTo.getVar().getDefinition().(MultiAssignmentDefinition).indexOf(index, target) and
nodeFrom.asExpr() = assign.getValue() and
(
c instanceof ListElementContent
or
c instanceof SetElementContent
or
c.(TupleElementContent).getIndex() = index
)
)
}
/** Data flows from a sequence to a call to `pop` on the sequence. */
predicate popReadStep(CfgNode nodeFrom, Content c, CfgNode nodeTo) {
// set.pop or list.pop

12
python/ql/test/experimental/dataflow/coverage/dataflow.expected
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@@ -61,6 +61,7 @@ edges
| test.py:0:0:0:0 | ModuleVariableNode for Global Variable SOURCE in Module test | test.py:492:33:492:38 | ControlFlowNode for SOURCE |
| test.py:0:0:0:0 | ModuleVariableNode for Global Variable SOURCE in Module test | test.py:497:39:497:44 | ControlFlowNode for SOURCE |
| test.py:0:0:0:0 | ModuleVariableNode for Global Variable SOURCE in Module test | test.py:509:9:509:14 | ControlFlowNode for SOURCE |
| test.py:0:0:0:0 | ModuleVariableNode for Global Variable SOURCE in Module test | test.py:521:10:521:15 | ControlFlowNode for SOURCE |
| test.py:0:0:0:0 | ModuleVariableNode for Global Variable SOURCE in Module test | test.py:596:16:596:21 | ControlFlowNode for SOURCE |
| test.py:20:1:20:6 | GSSA Variable SOURCE | test.py:0:0:0:0 | ModuleVariableNode for Global Variable SOURCE in Module test |
| test.py:20:10:20:17 | ControlFlowNode for Str | test.py:20:1:20:6 | GSSA Variable SOURCE |
@@ -180,6 +181,10 @@ edges
| test.py:497:39:497:44 | ControlFlowNode for SOURCE | test.py:497:10:497:45 | KwOverflowNode for f_extra_keyword() [Dictionary element at key b] |
| test.py:509:9:509:14 | ControlFlowNode for SOURCE | test.py:511:10:511:10 | ControlFlowNode for a |
| test.py:509:9:509:14 | ControlFlowNode for SOURCE | test.py:516:10:516:10 | ControlFlowNode for b |
| test.py:521:10:521:15 | ControlFlowNode for SOURCE | test.py:521:10:521:26 | ControlFlowNode for Tuple [Tuple element at index 0] |
| test.py:521:10:521:26 | ControlFlowNode for Tuple [Tuple element at index 0] | test.py:522:12:522:12 | ControlFlowNode for t [Tuple element at index 0] |
| test.py:522:5:522:5 | SSA variable a | test.py:523:10:523:10 | ControlFlowNode for a |
| test.py:522:12:522:12 | ControlFlowNode for t [Tuple element at index 0] | test.py:522:5:522:5 | SSA variable a |
| test.py:596:16:596:21 | ControlFlowNode for SOURCE | test.py:599:10:599:36 | ControlFlowNode for return_from_inner_scope() |
nodes
| datamodel.py:0:0:0:0 | ModuleVariableNode for Global Variable SOURCE in Module datamodel | semmle.label | ModuleVariableNode for Global Variable SOURCE in Module datamodel |
@@ -357,6 +362,11 @@ nodes
| test.py:509:9:509:14 | ControlFlowNode for SOURCE | semmle.label | ControlFlowNode for SOURCE |
| test.py:511:10:511:10 | ControlFlowNode for a | semmle.label | ControlFlowNode for a |
| test.py:516:10:516:10 | ControlFlowNode for b | semmle.label | ControlFlowNode for b |
| test.py:521:10:521:15 | ControlFlowNode for SOURCE | semmle.label | ControlFlowNode for SOURCE |
| test.py:521:10:521:26 | ControlFlowNode for Tuple [Tuple element at index 0] | semmle.label | ControlFlowNode for Tuple [Tuple element at index 0] |
| test.py:522:5:522:5 | SSA variable a | semmle.label | SSA variable a |
| test.py:522:12:522:12 | ControlFlowNode for t [Tuple element at index 0] | semmle.label | ControlFlowNode for t [Tuple element at index 0] |
| test.py:523:10:523:10 | ControlFlowNode for a | semmle.label | ControlFlowNode for a |
| test.py:596:16:596:21 | ControlFlowNode for SOURCE | semmle.label | ControlFlowNode for SOURCE |
| test.py:599:10:599:36 | ControlFlowNode for return_from_inner_scope() | semmle.label | ControlFlowNode for return_from_inner_scope() |
#select
@@ -456,5 +466,7 @@ nodes
| test.py:511:10:511:10 | ControlFlowNode for a | test.py:509:9:509:14 | ControlFlowNode for SOURCE | test.py:511:10:511:10 | ControlFlowNode for a | Flow found |
| test.py:516:10:516:10 | ControlFlowNode for b | test.py:20:10:20:17 | ControlFlowNode for Str | test.py:516:10:516:10 | ControlFlowNode for b | Flow found |
| test.py:516:10:516:10 | ControlFlowNode for b | test.py:509:9:509:14 | ControlFlowNode for SOURCE | test.py:516:10:516:10 | ControlFlowNode for b | Flow found |
| test.py:523:10:523:10 | ControlFlowNode for a | test.py:20:10:20:17 | ControlFlowNode for Str | test.py:523:10:523:10 | ControlFlowNode for a | Flow found |
| test.py:523:10:523:10 | ControlFlowNode for a | test.py:521:10:521:15 | ControlFlowNode for SOURCE | test.py:523:10:523:10 | ControlFlowNode for a | Flow found |
| test.py:599:10:599:36 | ControlFlowNode for return_from_inner_scope() | test.py:20:10:20:17 | ControlFlowNode for Str | test.py:599:10:599:36 | ControlFlowNode for return_from_inner_scope() | Flow found |
| test.py:599:10:599:36 | ControlFlowNode for return_from_inner_scope() | test.py:596:16:596:21 | ControlFlowNode for SOURCE | test.py:599:10:599:36 | ControlFlowNode for return_from_inner_scope() | Flow found |

2
python/ql/test/experimental/dataflow/coverage/test.py
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@@ -520,7 +520,7 @@ def test_swap():
def test_unpacking_assignment():
t = (SOURCE, NONSOURCE)
a, b = t
SINK(a) # Flow missing
SINK(a)
SINK_F(b)