Merge pull request #15695 from github/tausbn/python-add-copy-method-as-copy-step

Python: Add `.copy()` method call as copy step

Author: RasmusWL

python/ql/lib/semmle/python/dataflow/new/internal/TaintTrackingPrivate.qll

@@ -195,6 +195,8 @@ predicate copyStep(DataFlow::CfgNode nodeFrom, DataFlow::CfgNode nodeTo) {
     call = API::moduleImport("copy").getMember(["copy", "deepcopy"]).getACall() and
     call.getArg(0) = nodeFrom
   )
+  or
+  nodeTo.(DataFlow::MethodCallNode).calls(nodeFrom, "copy")
 }
 
 /**

python/ql/test/query-tests/Functions/ModificationOfParameterWithDefault/test.py

@@ -216,3 +216,9 @@ def flow_from_within_deepcopy_fp():
 def flow_through_deepcopy_fp(x=[]):
     y = deepcopy(x)
     y.append(1)
+
+# Use of copy method:
+
+def flow_through_copy_fp(x=[]):
+    y = x.copy()
+    y.append(1)