Report more cases of null dereference as empty vector access

Differential Revision: D3429002

fbshipit-source-id: e87960f

infer/src/backend/errdesc.ml

@@ -43,6 +43,14 @@ let method_of_pointer_wrapper pname =
 let is_vector_method pname =
   is_method_of_objc_cpp_class pname [vector_class]
 
+let is_special_field class_names field_name_opt field =
+  let complete_fieldname = Ident.fieldname_to_complete_string field in
+  let field_ok =
+    match field_name_opt with
+    | Some field_name -> Utils.string_contains field_name complete_fieldname
+    | None -> true in
+  is_one_of_classes complete_fieldname class_names && field_ok
+
 (** Check whether the hpred is a |-> representing a resource in the Racquire state *)
 let hpred_is_open_resource prop = function
   | Sil.Hpointsto(e, _, _) ->
@@ -798,9 +806,7 @@ let explain_dereference_access outermost_array is_nullable _de_opt prop =
         Some (if outermost_array then remove_outermost_array_access de else de) in
   let value_str = match de_opt with
     | Some (Sil.Darrow ((Sil.Dpvaraddr pvar), f) as de) ->
-        let complete_fieldname = Ident.fieldname_to_complete_string f in
-        if is_one_of_classes complete_fieldname smart_pointers &&
-           Utils.string_contains "data" complete_fieldname then
+        if is_special_field smart_pointers None f then
           Sil.dexp_to_string (Sil.Dpvaraddr pvar)
         else Sil.dexp_to_string de
     | Some de ->
@@ -835,7 +841,10 @@ let create_dereference_desc
            | _ -> desc)
       | Some (Sil.Dretcall (Dconst (Cfun pname), this_dexp :: _, loc, _ ))
         when is_vector_method pname ->
-          Localise.desc_empty_vector_access pname (Sil.dexp_to_string this_dexp) loc
+          Localise.desc_empty_vector_access (Some pname) (Sil.dexp_to_string this_dexp) loc
+      | Some (Sil.Darrow (dexp, fieldname))
+        when is_special_field [vector_class] (Some "beginPtr") fieldname ->
+          Localise.desc_empty_vector_access None (Sil.dexp_to_string dexp) loc
       | _ -> desc
     else desc in
   if use_buckets then Buckets.classify_access desc access_opt' de_opt is_nullable

infer/src/backend/localise.ml

@@ -650,9 +650,9 @@ let desc_divide_by_zero expr_str loc =
       (at_line tags loc) in
   { no_desc with descriptions = [description]; tags = !tags }
 
-let desc_empty_vector_access pname object_str loc =
+let desc_empty_vector_access pname_opt object_str loc =
   let vector_str = Format.sprintf "Vector %s" object_str in
-  let desc = access_str_empty (Some pname) in
+  let desc = access_str_empty pname_opt in
   let tags = desc.tags in
   Tags.add tags Tags.empty_vector_access object_str;
   let descriptions = [vector_str; desc.problem_str; (at_line tags loc)] in

infer/src/backend/localise.mli

@@ -203,7 +203,7 @@ val desc_deallocate_static_memory : string -> Procname.t -> Location.t -> error_
 
 val desc_divide_by_zero : string -> Location.t -> error_desc
 
-val desc_empty_vector_access : Procname.t -> string -> Location.t -> error_desc
+val desc_empty_vector_access : Procname.t option -> string -> Location.t -> error_desc
 
 val is_empty_vector_access_desc : error_desc -> bool
 

infer/tests/codetoanalyze/cpp/errors/vector/empty_access.cpp

@@ -115,15 +115,37 @@ int vector_param_access(std::vector<int>& v) {
   return v.back(); // shouldn't report anything here
 }
 
-/*
-// FIXME: analyzer reports it as NULL_DEREFERENCE (B5) instead
-// of EMPTY_VECTOR_ACCESS
 int vector_as_param_empty() {
   std::vector<int> v;
   return vector_param_access(v);
-}*/
+}
 
 int vector_as_param_nonempty() {
   std::vector<int> v(1);
   return vector_param_access(v);
 }
+
+int vector_param_by_value_access(std::vector<int> v) {
+  return v.back(); // shouldn't report anything here
+}
+
+int vector_as_param_by_value_empty() {
+  std::vector<int> v;
+  return vector_param_by_value_access(v);
+}
+
+void vector_param_by_value_clear(std::vector<int> v) { v.clear(); }
+
+int vector_as_param_by_value_clear_no_crash() {
+  std::vector<int> v(1);
+  vector_param_by_value_clear(v);
+  return v[0];
+}
+
+void vector_param_clear(std::vector<int>& v) { v.clear(); }
+
+int vector_as_param_clear() {
+  std::vector<int> v(1);
+  vector_param_clear(v);
+  return v[0];
+}

infer/tests/endtoend/cpp/VectorEmptyAccessTest.java

@@ -55,7 +55,9 @@ public class VectorEmptyAccessTest {
         "assign_empty",
         "empty_check_access_empty",
         "size_check0_empty",
-        //"vector_as_param_empty",
+        "vector_as_param_empty",
+        "vector_as_param_clear",
+        "vector_as_param_by_value_empty"
     };
     InferResults inferResults = InferRunner.runInferCPP(inferCmd);
     assertThat(