github / github/codeql

UAF not flagged

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#15,806 2 comments 0 reactions 1 assignee Claimed by @mbg View on GitHub
C++ question
Dominant language
CodeQL
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Description

I borrowed the query from UseAfterFree.ql present in CodeQL repo and modified to include a custom free function, but the query is not flagging UAF.

```
import cpp
import semmle.code.cpp.dataflow.new.DataFlow
import semmle.code.cpp.ir.IR
import semmle.code.cpp.security.flowafterfree.FlowAfterFree
import semmle.code.cpp.security.flowafterfree.UseAfterFree
import UseAfterFreeTrace::PathGraph

module UseAfterFreeParam implements FlowFromFreeParamSig {
predicate isSink = isUse/2;

predicate isExcluded = isExcludedMmFreePageFromMdl/2;

predicate sourceSinkIsRelated = defaultSourceSinkIsRelated/2;
}

import UseAfterFreeParam

module UseAfterFreeTrace = FlowFromFree;

class FreeAddrInfo extends DeallocationExpr,FunctionCall {

FreeAddrInfo() {
this.getTarget().hasGlobalName("freeaddrinfo")
}

override Expr getFreedExpr(){
result = this.getArgument(0)
}
}

from UseAfterFreeTrace::PathNode source, UseAfterFreeTrace::PathNode sink, FreeAddrInfo dealloc
where
UseAfterFreeTrace::flowPath(source, sink) and
isFree(source.getNode(), _, _, dealloc)
select sink.getNode(), source, sink, "Memory may have been previously freed by $@.", dealloc,
dealloc.toString()
```

I'm trying to analyse https://nvd.nist.gov/vuln/detail/CVE-2021-38383

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