Add compress/lzw taint tracking

ql/src/semmle/go/frameworks/Stdlib.qll

@@ -10,6 +10,7 @@ import semmle.go.frameworks.stdlib.Bytes
 import semmle.go.frameworks.stdlib.CompressBzip2
 import semmle.go.frameworks.stdlib.CompressFlate
 import semmle.go.frameworks.stdlib.CompressGzip
+import semmle.go.frameworks.stdlib.CompressLzw
 
 /** A `String()` method. */
 class StringMethod extends TaintTracking::FunctionModel, Method {

ql/src/semmle/go/frameworks/stdlib/CompressLzw.qll

@@ -0,0 +1,27 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `compress/lzw` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `compress/lzw` package. */
+module CompressLzw {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func NewReader(r io.Reader, order Order, litWidth int) io.ReadCloser
+      hasQualifiedName("compress/lzw", "NewReader") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func NewWriter(w io.Writer, order Order, litWidth int) io.WriteCloser
+      hasQualifiedName("compress/lzw", "NewWriter") and
+      (inp.isResult() and outp.isParameter(0))
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}

ql/test/library-tests/semmle/go/frameworks/StdlibTaintFlow/CompressLzw.go

@@ -0,0 +1,35 @@
+// Code generated by https://github.com/gagliardetto/codebox. DO NOT EDIT.
+
+package main
+
+import (
+	"compress/lzw"
+	"io"
+)
+
+func TaintStepTest_CompressLzwNewReader_B0I0O0(sourceCQL interface{}) interface{} {
+	fromReader656 := sourceCQL.(io.Reader)
+	intoReadCloser414 := lzw.NewReader(fromReader656, 0, 0)
+	return intoReadCloser414
+}
+
+func TaintStepTest_CompressLzwNewWriter_B0I0O0(sourceCQL interface{}) interface{} {
+	fromWriteCloser518 := sourceCQL.(io.WriteCloser)
+	var intoWriter650 io.Writer
+	intermediateCQL := lzw.NewWriter(intoWriter650, 0, 0)
+	link(fromWriteCloser518, intermediateCQL)
+	return intoWriter650
+}
+
+func RunAllTaints_CompressLzw() {
+	{
+		source := newSource(0)
+		out := TaintStepTest_CompressLzwNewReader_B0I0O0(source)
+		sink(0, out)
+	}
+	{
+		source := newSource(1)
+		out := TaintStepTest_CompressLzwNewWriter_B0I0O0(source)
+		sink(1, out)
+	}
+}