CodeQL query to find integer casting issues

go-int-down-casting.ql

import go
import semmle.go.dataflow.DataFlow
import semmle.go.dataflow.TaintTracking

class IntegerSource extends Function {
  IntegerSource() {
    this.hasQualifiedName("strconv", "Atoi") or
    this.hasQualifiedName("strconv", "ParseInt")
  }
}

class IntegerDownCastingConfig extends TaintTracking::Configuration {
  IntegerDownCastingConfig() { this = "IntegerDownCastingConfig" }

  override predicate isSource(DataFlow::Node source) {
    exists(IntegerSource f |
      source.asExpr() = f.getACall().asExpr()
    )
  }

  override predicate isSink(DataFlow::Node sink) {
    exists(ConversionExpr expr |
      // expr.mayHaveSideEffects() and
      expr.getOperand() = sink.asExpr()
    )
  }
}

from IntegerDownCastingConfig cfg, DataFlow::PathNode source, DataFlow::PathNode sink
where cfg.hasFlowPath(source, sink)
select sink, source, sink