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C++: Performance fix for cpp/cleartext-storage-buffer #11596

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Merged
merged 3 commits into from
Dec 8, 2022
Merged

C++: Performance fix for cpp/cleartext-storage-buffer #11596

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b3d838d
C++: Define the sources more clearly and consistently (fixes performa…
geoffw0 Dec 7, 2022
4b8575b
C++: Simplify the query slightly.
geoffw0 Dec 7, 2022
a8b8b54
Update cpp/ql/src/Security/CWE/CWE-311/CleartextBufferWrite.ql
geoffw0 Dec 7, 2022
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33 changes: 25 additions & 8 deletions cpp/ql/src/Security/CWE/CWE-311/CleartextBufferWrite.ql
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,25 @@ import semmle.code.cpp.ir.dataflow.TaintTracking
import DataFlow::PathGraph

/**
* A taint flow configuration for flow from user input to a buffer write.
* A buffer write into a sensitive expression.
*/
class SensitiveBufferWrite extends Expr instanceof BufferWrite::BufferWrite {
SensitiveBufferWrite() { super.getDest() instanceof SensitiveExpr }

/**
* Gets a data source of this operation.
*/
Expr getASource() { result = super.getASource() }

/**
* Gets the destination buffer of this operation.
*/
Expr getDest() { result = super.getDest() }
}

/**
* A taint flow configuration for flow from user input to a buffer write
* into a sensitive expression.
*/
class ToBufferConfiguration extends TaintTracking::Configuration {
ToBufferConfiguration() { this = "ToBufferConfiguration" }
Expand All @@ -31,18 +49,17 @@ class ToBufferConfiguration extends TaintTracking::Configuration {
}

override predicate isSink(DataFlow::Node sink) {
exists(BufferWrite::BufferWrite w | w.getASource() = sink.asExpr())
exists(SensitiveBufferWrite w | w.getASource() = sink.asExpr())
}
}

from
ToBufferConfiguration config, BufferWrite::BufferWrite w, DataFlow::PathNode sourceNode,
DataFlow::PathNode sinkNode, FlowSource source, SensitiveExpr dest
ToBufferConfiguration config, SensitiveBufferWrite w, DataFlow::PathNode sourceNode,
DataFlow::PathNode sinkNode, FlowSource source
where
config.hasFlowPath(sourceNode, sinkNode) and
sourceNode.getNode() = source and
w.getASource() = sinkNode.getNode().asExpr() and
dest = w.getDest()
w.getASource() = sinkNode.getNode().asExpr()
select w, sourceNode, sinkNode,
"This write into buffer '" + dest.toString() + "' may contain unencrypted data from $@.", source,
"user input (" + source.getSourceType() + ")"
"This write into buffer '" + w.getDest().toString() + "' may contain unencrypted data from $@.",
source, "user input (" + source.getSourceType() + ")"