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Merged
merged 5 commits into from
May 5, 2022
Merged

Data flow: Introduce expectsContent #8870

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a50f18a
Data flow: Introduce `expectsContent`
hvitved Apr 22, 2022
6e2e844
Data flow: Sync files
hvitved Apr 22, 2022
da72ba4
Data flow: Add stub `expectsContent` for all languages
hvitved Apr 22, 2022
ac3bfa1
Data flow: Mention `expectsContent` in `dataflow.md`
hvitved Apr 22, 2022
74e9930
Address review comments
hvitved May 3, 2022
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69 changes: 60 additions & 9 deletions cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -498,23 +498,35 @@ private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuratio
}

// inline to reduce fan-out via `getAReadContent`
pragma[inline]
bindingset[c]
private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
exists(ContentSet cs |
readSet(node1, cs, node2, config) and
c = cs.getAReadContent()
pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
)
}

// inline to reduce fan-out via `getAReadContent`
pragma[inline]
bindingset[c]
private predicate clearsContentEx(NodeEx n, Content c) {
exists(ContentSet cs |
clearsContentCached(n.asNode(), cs) and
c = cs.getAReadContent()
pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
)
}

// inline to reduce fan-out via `getAReadContent`
bindingset[c]
private predicate expectsContentEx(NodeEx n, Content c) {
exists(ContentSet cs |
expectsContentCached(n.asNode(), cs) and
pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
)
}

pragma[nomagic]
private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }

pragma[nomagic]
private predicate store(
NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
Expand Down Expand Up @@ -793,7 +805,7 @@ private module Stage1 {
* by `revFlow`.
*/
pragma[nomagic]
private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
predicate revFlowIsReadAndStored(Content c, Configuration conf) {
revFlowConsCand(c, conf) and
revFlowStore(c, _, _, conf)
}
Expand Down Expand Up @@ -891,7 +903,7 @@ private module Stage1 {

pragma[nomagic]
predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
revFlowIsReadAndStored(pragma[only_bind_into](c), pragma[only_bind_into](config)) and
revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
read(n1, c, n2, pragma[only_bind_into](config)) and
revFlow(n2, pragma[only_bind_into](config))
}
Expand Down Expand Up @@ -1181,11 +1193,26 @@ private module Stage2 {

private predicate flowIntoCall = flowIntoCallNodeCand1/5;

pragma[nomagic]
private predicate expectsContentCand(NodeEx node, Configuration config) {
exists(Content c |
PrevStage::revFlow(node, pragma[only_bind_into](config)) and
PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
expectsContentEx(node, c)
)
}

bindingset[node, state, ap, config]
private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
exists(ap) and
not stateBarrier(node, state, config)
not stateBarrier(node, state, config) and
(
notExpectsContent(node)
or
ap = true and
expectsContentCand(node, config)
)
}

bindingset[ap, contentType]
Expand Down Expand Up @@ -1740,7 +1767,8 @@ private module LocalFlowBigStep {
private class FlowCheckNode extends NodeEx {
FlowCheckNode() {
castNode(this.asNode()) or
clearsContentCached(this.asNode(), _)
clearsContentCached(this.asNode(), _) or
expectsContentCached(this.asNode(), _)
}
}

Expand Down Expand Up @@ -1979,6 +2007,16 @@ private module Stage3 {
clearContent(node, ap.getHead().getContent(), config)
}

pragma[nomagic]
private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
exists(Content c |
PrevStage::revFlow(node, pragma[only_bind_into](config)) and
PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
expectsContentEx(node, c) and
c = ap.getHead().getContent()
)
}

pragma[nomagic]
private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }

Expand All @@ -1987,7 +2025,12 @@ private module Stage3 {
exists(state) and
exists(config) and
not clear(node, ap, config) and
if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
(if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
(
notExpectsContent(node)
or
expectsContentCand(node, ap, config)
)
}

bindingset[ap, contentType]
Expand Down Expand Up @@ -4609,6 +4652,10 @@ private module FlowExploration {
exists(PartialPathNodeRev mid |
revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
not clearsContentEx(node, ap.getHead()) and
(
notExpectsContent(node) or
expectsContentEx(node, ap.getHead())
) and
not fullBarrier(node, config) and
not stateBarrier(node, state, config) and
distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
Expand All @@ -4625,6 +4672,10 @@ private module FlowExploration {
not fullBarrier(node, config) and
not stateBarrier(node, state, config) and
not clearsContentEx(node, ap.getHead().getContent()) and
(
notExpectsContent(node) or
expectsContentEx(node, ap.getHead().getContent())
) and
if node.asNode() instanceof CastingNode
then compatibleTypes(node.getDataFlowType(), ap.getType())
else any()
Expand Down
69 changes: 60 additions & 9 deletions cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -498,23 +498,35 @@ private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuratio
}

// inline to reduce fan-out via `getAReadContent`
pragma[inline]
bindingset[c]
private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
exists(ContentSet cs |
readSet(node1, cs, node2, config) and
c = cs.getAReadContent()
pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
)
}

// inline to reduce fan-out via `getAReadContent`
pragma[inline]
bindingset[c]
private predicate clearsContentEx(NodeEx n, Content c) {
exists(ContentSet cs |
clearsContentCached(n.asNode(), cs) and
c = cs.getAReadContent()
pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
)
}

// inline to reduce fan-out via `getAReadContent`
bindingset[c]
private predicate expectsContentEx(NodeEx n, Content c) {
exists(ContentSet cs |
expectsContentCached(n.asNode(), cs) and
pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
)
}

pragma[nomagic]
private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }

pragma[nomagic]
private predicate store(
NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
Expand Down Expand Up @@ -793,7 +805,7 @@ private module Stage1 {
* by `revFlow`.
*/
pragma[nomagic]
private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
predicate revFlowIsReadAndStored(Content c, Configuration conf) {
revFlowConsCand(c, conf) and
revFlowStore(c, _, _, conf)
}
Expand Down Expand Up @@ -891,7 +903,7 @@ private module Stage1 {

pragma[nomagic]
predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
revFlowIsReadAndStored(pragma[only_bind_into](c), pragma[only_bind_into](config)) and
revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
read(n1, c, n2, pragma[only_bind_into](config)) and
revFlow(n2, pragma[only_bind_into](config))
}
Expand Down Expand Up @@ -1181,11 +1193,26 @@ private module Stage2 {

private predicate flowIntoCall = flowIntoCallNodeCand1/5;

pragma[nomagic]
private predicate expectsContentCand(NodeEx node, Configuration config) {
exists(Content c |
PrevStage::revFlow(node, pragma[only_bind_into](config)) and
PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
expectsContentEx(node, c)
)
}

bindingset[node, state, ap, config]
private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
exists(ap) and
not stateBarrier(node, state, config)
not stateBarrier(node, state, config) and
(
notExpectsContent(node)
or
ap = true and
expectsContentCand(node, config)
)
}

bindingset[ap, contentType]
Expand Down Expand Up @@ -1740,7 +1767,8 @@ private module LocalFlowBigStep {
private class FlowCheckNode extends NodeEx {
FlowCheckNode() {
castNode(this.asNode()) or
clearsContentCached(this.asNode(), _)
clearsContentCached(this.asNode(), _) or
expectsContentCached(this.asNode(), _)
}
}

Expand Down Expand Up @@ -1979,6 +2007,16 @@ private module Stage3 {
clearContent(node, ap.getHead().getContent(), config)
}

pragma[nomagic]
private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
exists(Content c |
PrevStage::revFlow(node, pragma[only_bind_into](config)) and
PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
expectsContentEx(node, c) and
c = ap.getHead().getContent()
)
}

pragma[nomagic]
private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }

Expand All @@ -1987,7 +2025,12 @@ private module Stage3 {
exists(state) and
exists(config) and
not clear(node, ap, config) and
if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
(if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
(
notExpectsContent(node)
or
expectsContentCand(node, ap, config)
)
}

bindingset[ap, contentType]
Expand Down Expand Up @@ -4609,6 +4652,10 @@ private module FlowExploration {
exists(PartialPathNodeRev mid |
revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
not clearsContentEx(node, ap.getHead()) and
(
notExpectsContent(node) or
expectsContentEx(node, ap.getHead())
) and
not fullBarrier(node, config) and
not stateBarrier(node, state, config) and
distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
Expand All @@ -4625,6 +4672,10 @@ private module FlowExploration {
not fullBarrier(node, config) and
not stateBarrier(node, state, config) and
not clearsContentEx(node, ap.getHead().getContent()) and
(
notExpectsContent(node) or
expectsContentEx(node, ap.getHead().getContent())
) and
if node.asNode() instanceof CastingNode
then compatibleTypes(node.getDataFlowType(), ap.getType())
else any()
Expand Down
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