bpo-46476: Fix memory leak in code objects generated by deepfreeze

Misc/NEWS.d/next/Core and Builtins/2022-01-24-15-39-34.bpo-46476.cvP1Mr.rst

@@ -0,0 +1 @@
+Fix memory leak in code objects generated by deepfreeze. Patch by Kumar Aditya.

Modules/main.c

@@ -28,6 +28,8 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
+/* For deepfrozen modules */
+extern void _Py_Deepfreeze_Fini(void);
 
 /* --- pymain_init() ---------------------------------------------- */
 
@@ -621,6 +623,7 @@ pymain_free(void)
     _PyPathConfig_ClearGlobal();
     _Py_ClearStandardStreamEncoding();
     _Py_ClearArgcArgv();
+    _Py_Deepfreeze_Fini();
     _PyRuntime_Finalize();
 }
 

Programs/_bootstrap_python.c

@@ -103,3 +103,7 @@ main(int argc, char **argv)
     }
     Py_ExitStatusException(status);
 }
+
+
+void _Py_Deepfreeze_Fini(void) {
+};

Programs/_freeze_module.c

@@ -234,4 +234,7 @@ main(int argc, char *argv[])
     PyErr_Print();
     Py_Finalize();
     return 1;
-}
+};
+
+void _Py_Deepfreeze_Fini(void) {
+};

Tools/scripts/deepfreeze.py

@@ -109,11 +109,17 @@ def __init__(self, file: TextIO) -> None:
         self.cache: Dict[tuple[type, object, str], str] = {}
         self.hits, self.misses = 0, 0
         self.patchups: list[str] = []
+        self.deallocs: list[str] = []
         self.write('#include "Python.h"')
         self.write('#include "internal/pycore_gc.h"')
         self.write('#include "internal/pycore_code.h"')
         self.write('#include "internal/pycore_long.h"')
         self.write("")
+        with self.block("static void dealloc_codeobject(PyCodeObject co)", ";"):
+            self.write("PyMem_Free(co.co_quickened);")
+            self.write("PyMem_Free(co.co_extra);")
+            with self.block("if (co.co_weakreflist != NULL)", ";"):
+                self.write("PyObject_ClearWeakRefs((PyObject *)&co);")         
 
     @contextlib.contextmanager
     def indent(self) -> None:
@@ -277,6 +283,7 @@ def generate_code(self, name: str, code: types.CodeType) -> str:
             self.write(f".co_varnames = {co_varnames},")
             self.write(f".co_cellvars = {co_cellvars},")
             self.write(f".co_freevars = {co_freevars},")
+        self.deallocs.append(f"dealloc_codeobject({name});")
         return f"& {name}.ob_base"
 
     def generate_tuple(self, name: str, t: Tuple[object, ...]) -> str:
@@ -440,6 +447,9 @@ def generate(args: list[str], output: TextIO) -> None:
             else:
                 code = compile(fd.read(), f"<frozen {modname}>", "exec")
             printer.generate_file(modname, code)
+    with printer.block(f"void _Py_Deepfreeze_Fini(void)"):
+            for p in printer.deallocs:
+                printer.write(p)
     if verbose:
         print(f"Cache hits: {printer.hits}, misses: {printer.misses}")