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C#: Simplify, getASuccessor is pruned now. #15547

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Merged
aschackmull merged 1 commit into from
Feb 8, 2024
Merged

C#: Simplify, getASuccessor is pruned now. #15547

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17 changes: 5 additions & 12 deletions csharp/ql/lib/semmle/code/csharp/dataflow/internal/ContentDataFlow.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -277,10 +277,6 @@ module Global<ConfigSig ContentConfig> {
}
}

// important to use `edges` and not `PathNode::getASuccessor()`, as the latter
// is not pruned for reachability
private predicate pathSucc = Flow::PathGraph::edges/2;

/**
* Provides a big-step flow relation, where flow stops at read/store steps that
* must be recorded, and flow via `subpaths` such that reads/stores inside
Expand All @@ -290,10 +286,7 @@ module Global<ConfigSig ContentConfig> {
private predicate reachesSink(Flow::PathNode node) {
FlowConfig::isSink(node.getNode(), node.getState())
or
exists(Flow::PathNode mid |
pathSucc(node, mid) and
reachesSink(mid)
)
reachesSink(node.getASuccessor())
}

/**
Expand All @@ -302,7 +295,7 @@ module Global<ConfigSig ContentConfig> {
*/
pragma[nomagic]
private predicate excludeStep(Flow::PathNode pred, Flow::PathNode succ) {
pathSucc(pred, succ) and
pred.getASuccessor() = succ and
(
// we need to record reads/stores inside summarized callables
Flow::PathGraph::subpaths(pred, _, _, succ)
Expand Down Expand Up @@ -356,7 +349,7 @@ module Global<ConfigSig ContentConfig> {

pragma[nomagic]
private predicate step(Flow::PathNode pred, Flow::PathNode succ) {
pathSucc(pred, succ) and
pred.getASuccessor() = succ and
not excludeStep(pred, succ)
}

Expand Down Expand Up @@ -471,7 +464,7 @@ module Global<ConfigSig ContentConfig> {
exists(Flow::PathNode mid |
nodeReaches(source, scReads, scStores, mid, reads, stores) and
storeStep(mid.getNode(), mid.getState(), c, node.getNode(), node.getState()) and
pathSucc(mid, node)
mid.getASuccessor() = node
)
}

Expand All @@ -483,7 +476,7 @@ module Global<ConfigSig ContentConfig> {
exists(Flow::PathNode mid |
nodeReaches(source, scReads, scStores, mid, reads, stores) and
readStep(mid.getNode(), mid.getState(), c, node.getNode(), node.getState()) and
pathSucc(mid, node)
mid.getASuccessor() = node
)
}

Expand Down