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UseAfterFree.ql
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UseAfterFree.ql
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/**
* @name Potential use after free
* @description An allocated memory block is used after it has been freed. Behavior in such cases is undefined and can cause memory corruption.
* @kind path-problem
* @precision high
* @id cpp/use-after-free
* @problem.severity warning
* @security-severity 9.3
* @tags reliability
* security
* external/cwe/cwe-416
*/
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<UseAfterFreeParam>;
from UseAfterFreeTrace::PathNode source, UseAfterFreeTrace::PathNode sink, DeallocationExpr 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()