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

Include/internal/pycore_pylifecycle.h

@@ -83,6 +83,7 @@ extern void _PyWarnings_Fini(PyInterpreterState *interp);
 extern void _PyAST_Fini(PyInterpreterState *interp);
 extern void _PyAtExit_Fini(PyInterpreterState *interp);
 extern void _PyThread_FiniType(PyInterpreterState *interp);
+extern void _Py_Deepfreeze_Fini(void);
 
 extern PyStatus _PyGILState_Init(_PyRuntimeState *runtime);
 extern PyStatus _PyGILState_SetTstate(PyThreadState *tstate);

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.

Programs/_bootstrap_python.c

@@ -14,6 +14,12 @@
 #include "Python/frozen_modules/importlib._bootstrap_external.h"
 /* End includes */
 
+/* Empty finalizer for deepfrozen modules*/
+void
+_Py_Deepfreeze_Fini(void) 
+{
+}
+
 /* Note that a negative size indicates a package. */
 
 static const struct _frozen bootstrap_modules[] = {
@@ -103,3 +109,4 @@ main(int argc, char **argv)
     }
     Py_ExitStatusException(status);
 }
+

Programs/_freeze_module.c

@@ -22,6 +22,12 @@
 #include <unistd.h>
 #endif
 
+/* Empty finalizer for deepfrozen modules */
+void
+_Py_Deepfreeze_Fini(void)
+{
+}
+
 /* To avoid a circular dependency on frozen.o, we create our own structure
    of frozen modules instead, left deliberately blank so as to avoid
    unintentional import of a stale version of _frozen_importlib. */
@@ -235,3 +241,4 @@ main(int argc, char *argv[])
     Py_Finalize();
     return 1;
 }
+

Python/pylifecycle.c

@@ -1723,6 +1723,7 @@ finalize_interp_clear(PyThreadState *tstate)
         _Py_HashRandomization_Fini();
         _PyArg_Fini();
         _Py_ClearFileSystemEncoding();
+        _Py_Deepfreeze_Fini();
     }
 
     finalize_interp_types(tstate->interp);

Tools/scripts/deepfreeze.py

@@ -109,6 +109,7 @@ 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"')
@@ -277,6 +278,7 @@ 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}, (_Py_CODEUNIT *) {removesuffix(co_code, '.ob_base.ob_base')}.ob_sval);")
         return f"& {name}.ob_base"
 
     def generate_tuple(self, name: str, t: Tuple[object, ...]) -> str:
@@ -440,6 +442,18 @@ 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("static void\ndealloc_codeobject(PyCodeObject *co, _Py_CODEUNIT *firstinstr)"):
+            printer.write("PyMem_Free(co->co_quickened);")
+            printer.write("co->co_quickened = NULL;")
+            printer.write("PyMem_Free(co->co_extra);")
+            printer.write("co->co_extra = NULL;")
+            printer.write("co->co_firstinstr = firstinstr;")
+            with printer.block("if (co->co_weakreflist != NULL)"):
+                printer.write("PyObject_ClearWeakRefs((PyObject *)co);")   
+                printer.write("co->co_weakreflist = NULL;")   
+    with printer.block(f"void\n_Py_Deepfreeze_Fini(void)"):
+            for p in printer.deallocs:
+                printer.write(p)
     if verbose:
         print(f"Cache hits: {printer.hits}, misses: {printer.misses}")