python: add support for lower bound position

Author: yoff

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

@@ -57,6 +57,9 @@ newtype TParameterPosition =
     // parameter positions available.
     FlowSummaryImpl::ParsePositions::isParsedPositionalArgumentPosition(_, index)
   } or
+  TPositionalParameterLowerBoundPosition(int pos) {
+    FlowSummaryImpl::ParsePositions::isParsedArgumentLowerBoundPosition(_, pos)
+  } or
   TKeywordParameterPosition(string name) {
     name = any(Parameter p).getName()
     or
@@ -91,6 +94,9 @@ class ParameterPosition extends TParameterPosition {
   /** Holds if this position represents a positional parameter at (0-based) `index`. */
   predicate isPositional(int index) { this = TPositionalParameterPosition(index) }
 
+  /** Holds if this position represents any positional parameter starting from position `pos`. */
+  predicate isPositionalLowerBound(int pos) { this = TPositionalParameterLowerBoundPosition(pos) }
+
   /** Holds if this position represents a keyword parameter named `name`. */
   predicate isKeyword(string name) { this = TKeywordParameterPosition(name) }
 
@@ -123,6 +129,8 @@ class ParameterPosition extends TParameterPosition {
     or
     exists(int index | this.isPositional(index) and result = "position " + index)
     or
+    exists(int pos | this.isPositionalLowerBound(pos) and result = "position " + pos + "..")
+    or
     exists(string name | this.isKeyword(name) and result = "keyword " + name)
     or
     exists(int index | this.isStarArgs(index) and result = "*args at " + index)
@@ -211,6 +219,10 @@ predicate parameterMatch(ParameterPosition ppos, ArgumentPosition apos) {
   or
   exists(int index | ppos.isPositional(index) and apos.isPositional(index))
   or
+  exists(int index1, int index2 |
+    ppos.isPositionalLowerBound(index1) and apos.isPositional(index2) and index2 >= index1
+  )
+  or
   exists(string name | ppos.isKeyword(name) and apos.isKeyword(name))
   or
   exists(int index | ppos.isStarArgs(index) and apos.isStarArgs(index))
@@ -360,6 +372,10 @@ abstract class DataFlowFunction extends DataFlowCallable, TFunction {
       result.getParameter() = func.getArg(index + this.positionalOffset())
     )
     or
+    exists(int index1, int index2 | ppos.isPositionalLowerBound(index1) and index2 >= index1 |
+      result.getParameter() = func.getArg(index2 + this.positionalOffset())
+    )
+    or
     exists(string name | ppos.isKeyword(name) | result.getParameter() = func.getArgByName(name))
     or
     // `*args`

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

@@ -195,6 +195,11 @@ module ParsePositions {
     i = AccessPath::parseInt(c)
   }
 
+  predicate isParsedArgumentLowerBoundPosition(string c, int i) {
+    isArgBody(c) and
+    i = AccessPath::parseLowerBound(c)
+  }
+
   predicate isParsedKeywordArgumentPosition(string c, string argName) {
     isArgBody(c) and
     c = argName + ":"