[Lldb-commits] [PATCH] D147007: [lldb] Fix double free in python bindings error handling.

[Jorge Gorbe Moya via Phabricator via lldb-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG4a38d3326895: [lldb] Fix double free in python bindings 
error handling. (authored by jgorbe).

Changed prior to commit:
  https://reviews.llvm.org/D147007?vs=508811&id=508827#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147007/new/

https://reviews.llvm.org/D147007

Files:
  lldb/bindings/python/python-typemaps.swig


Index: lldb/bindings/python/python-typemaps.swig
===================================================================
--- lldb/bindings/python/python-typemaps.swig
+++ lldb/bindings/python/python-typemaps.swig
@@ -1,4 +1,10 @@
-/* Typemap definitions, to allow SWIG to properly handle 'char**' data types. 
*/
+/* Typemap definitions, to allow SWIG to properly handle 'char**' data types.
+
+NOTE: If there's logic to free memory in a %typemap(freearg), it will also be
+run if you call SWIG_fail on an error path. Don't manually free() an argument
+AND call SWIG_fail at the same time, because it will result in a double free.
+
+*/
 
 %inline %{
 
@@ -17,7 +23,6 @@
       PythonString py_str = list.GetItemAtIndex(i).AsType<PythonString>();
       if (!py_str.IsAllocated()) {
         PyErr_SetString(PyExc_TypeError, "list must contain strings");
-        free($1);
         SWIG_fail;
       }
 
@@ -294,12 +299,10 @@
       PyObject *o = PyList_GetItem($input, i);
       if (!SetNumberFromPyObject($1[i], o)) {
         PyErr_SetString(PyExc_TypeError, "list must contain numbers");
-        free($1);
         SWIG_fail;
       }
 
       if (PyErr_Occurred()) {
-        free($1);
         SWIG_fail;
       }
     }



Index: lldb/bindings/python/python-typemaps.swig
===================================================================
--- lldb/bindings/python/python-typemaps.swig
+++ lldb/bindings/python/python-typemaps.swig
@@ -1,4 +1,10 @@
-/* Typemap definitions, to allow SWIG to properly handle 'char**' data types. */
+/* Typemap definitions, to allow SWIG to properly handle 'char**' data types.
+
+NOTE: If there's logic to free memory in a %typemap(freearg), it will also be
+run if you call SWIG_fail on an error path. Don't manually free() an argument
+AND call SWIG_fail at the same time, because it will result in a double free.
+
+*/
 
 %inline %{
 
@@ -17,7 +23,6 @@
       PythonString py_str = list.GetItemAtIndex(i).AsType<PythonString>();
       if (!py_str.IsAllocated()) {
         PyErr_SetString(PyExc_TypeError, "list must contain strings");
-        free($1);
         SWIG_fail;
       }
 
@@ -294,12 +299,10 @@
       PyObject *o = PyList_GetItem($input, i);
       if (!SetNumberFromPyObject($1[i], o)) {
         PyErr_SetString(PyExc_TypeError, "list must contain numbers");
-        free($1);
         SWIG_fail;
       }
 
       if (PyErr_Occurred()) {
-        free($1);
         SWIG_fail;
       }
     }

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