[Python-checkins] bpo-40887: Don't use finalized free lists (GH-20700)
Victor Stinner
webhook-mailer at python.org
Sun Jun 7 20:14:55 EDT 2020
https://github.com/python/cpython/commit/bcb198385dee469d630a184182df9dc1463e2c47
commit: bcb198385dee469d630a184182df9dc1463e2c47
branch: master
author: Victor Stinner <vstinner at python.org>
committer: GitHub <noreply at github.com>
date: 2020-06-08T02:14:47+02:00
summary:
bpo-40887: Don't use finalized free lists (GH-20700)
In debug mode, ensure that free lists are no longer used after being
finalized. Set numfree to -1 in finalization functions
(eg. _PyList_Fini()), and then check that numfree is not equal to -1
before using a free list (e.g list_dealloc()).
files:
M Objects/floatobject.c
M Objects/frameobject.c
M Objects/genobject.c
M Objects/listobject.c
M Objects/tupleobject.c
M Python/context.c
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index d72fd21f95faf..65625fe88cad8 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -116,6 +116,10 @@ PyFloat_FromDouble(double fval)
struct _Py_float_state *state = &interp->float_state;
PyFloatObject *op = state->free_list;
if (op != NULL) {
+#ifdef Py_DEBUG
+ // PyFloat_FromDouble() must not be called after _PyFloat_Fini()
+ assert(state->numfree != -1);
+#endif
state->free_list = (PyFloatObject *) Py_TYPE(op);
state->numfree--;
}
@@ -219,6 +223,10 @@ float_dealloc(PyFloatObject *op)
if (PyFloat_CheckExact(op)) {
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_float_state *state = &interp->float_state;
+#ifdef Py_DEBUG
+ // float_dealloc() must not be called after _PyFloat_Fini()
+ assert(state->numfree != -1);
+#endif
if (state->numfree >= PyFloat_MAXFREELIST) {
PyObject_FREE(op);
return;
@@ -1984,10 +1992,11 @@ void
_PyFloat_ClearFreeList(PyThreadState *tstate)
{
struct _Py_float_state *state = &tstate->interp->float_state;
- PyFloatObject *f = state->free_list, *next;
- for (; f; f = next) {
- next = (PyFloatObject*) Py_TYPE(f);
+ PyFloatObject *f = state->free_list;
+ while (f != NULL) {
+ PyFloatObject *next = (PyFloatObject*) Py_TYPE(f);
PyObject_FREE(f);
+ f = next;
}
state->free_list = NULL;
state->numfree = 0;
@@ -1997,6 +2006,10 @@ void
_PyFloat_Fini(PyThreadState *tstate)
{
_PyFloat_ClearFreeList(tstate);
+#ifdef Py_DEBUG
+ struct _Py_float_state *state = &tstate->interp->float_state;
+ state->numfree = -1;
+#endif
}
/* Print summary info about the state of the optimized allocator */
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 0fe9f2a6666b2..0dad42ee7bff3 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -595,6 +595,10 @@ frame_dealloc(PyFrameObject *f)
else {
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_frame_state *state = &interp->frame;
+#ifdef Py_DEBUG
+ // frame_dealloc() must not be called after _PyFrame_Fini()
+ assert(state->numfree != -1);
+#endif
if (state->numfree < PyFrame_MAXFREELIST) {
++state->numfree;
f->f_back = state->free_list;
@@ -790,6 +794,10 @@ frame_alloc(PyCodeObject *code)
}
}
else {
+#ifdef Py_DEBUG
+ // frame_alloc() must not be called after _PyFrame_Fini()
+ assert(state->numfree != -1);
+#endif
assert(state->numfree > 0);
--state->numfree;
f = state->free_list;
@@ -1188,6 +1196,10 @@ void
_PyFrame_Fini(PyThreadState *tstate)
{
_PyFrame_ClearFreeList(tstate);
+#ifdef Py_DEBUG
+ struct _Py_frame_state *state = &tstate->interp->frame;
+ state->numfree = -1;
+#endif
}
/* Print summary info about the state of the optimized allocator */
diff --git a/Objects/genobject.c b/Objects/genobject.c
index f7dbfd7486419..4207d5326cca1 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -1430,6 +1430,11 @@ void
_PyAsyncGen_Fini(PyThreadState *tstate)
{
_PyAsyncGen_ClearFreeLists(tstate);
+#ifdef Py_DEBUG
+ struct _Py_async_gen_state *state = &tstate->interp->async_gen;
+ state->value_numfree = -1;
+ state->asend_numfree = -1;
+#endif
}
@@ -1474,6 +1479,10 @@ async_gen_asend_dealloc(PyAsyncGenASend *o)
Py_CLEAR(o->ags_sendval);
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_async_gen_state *state = &interp->async_gen;
+#ifdef Py_DEBUG
+ // async_gen_asend_dealloc() must not be called after _PyAsyncGen_Fini()
+ assert(state->asend_numfree != -1);
+#endif
if (state->asend_numfree < _PyAsyncGen_MAXFREELIST) {
assert(PyAsyncGenASend_CheckExact(o));
state->asend_freelist[state->asend_numfree++] = o;
@@ -1632,6 +1641,10 @@ async_gen_asend_new(PyAsyncGenObject *gen, PyObject *sendval)
PyAsyncGenASend *o;
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_async_gen_state *state = &interp->async_gen;
+#ifdef Py_DEBUG
+ // async_gen_asend_new() must not be called after _PyAsyncGen_Fini()
+ assert(state->asend_numfree != -1);
+#endif
if (state->asend_numfree) {
state->asend_numfree--;
o = state->asend_freelist[state->asend_numfree];
@@ -1667,6 +1680,10 @@ async_gen_wrapped_val_dealloc(_PyAsyncGenWrappedValue *o)
Py_CLEAR(o->agw_val);
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_async_gen_state *state = &interp->async_gen;
+#ifdef Py_DEBUG
+ // async_gen_wrapped_val_dealloc() must not be called after _PyAsyncGen_Fini()
+ assert(state->value_numfree != -1);
+#endif
if (state->value_numfree < _PyAsyncGen_MAXFREELIST) {
assert(_PyAsyncGenWrappedValue_CheckExact(o));
state->value_freelist[state->value_numfree++] = o;
@@ -1737,6 +1754,10 @@ _PyAsyncGenValueWrapperNew(PyObject *val)
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_async_gen_state *state = &interp->async_gen;
+#ifdef Py_DEBUG
+ // _PyAsyncGenValueWrapperNew() must not be called after _PyAsyncGen_Fini()
+ assert(state->value_numfree != -1);
+#endif
if (state->value_numfree) {
state->value_numfree--;
o = state->value_freelist[state->value_numfree];
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 043256d8adbf5..22cdbe3cfdd41 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -111,6 +111,10 @@ void
_PyList_Fini(PyThreadState *tstate)
{
_PyList_ClearFreeList(tstate);
+#ifdef Py_DEBUG
+ struct _Py_list_state *state = &tstate->interp->list;
+ state->numfree = -1;
+#endif
}
/* Print summary info about the state of the optimized allocator */
@@ -135,6 +139,10 @@ PyList_New(Py_ssize_t size)
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_list_state *state = &interp->list;
PyListObject *op;
+#ifdef Py_DEBUG
+ // PyList_New() must not be called after _PyList_Fini()
+ assert(state->numfree != -1);
+#endif
if (state->numfree) {
state->numfree--;
op = state->free_list[state->numfree];
@@ -330,6 +338,10 @@ list_dealloc(PyListObject *op)
}
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_list_state *state = &interp->list;
+#ifdef Py_DEBUG
+ // list_dealloc() must not be called after _PyList_Fini()
+ assert(state->numfree != -1);
+#endif
if (state->numfree < PyList_MAXFREELIST && PyList_CheckExact(op)) {
state->free_list[state->numfree++] = op;
}
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 951cd1faf7e8f..8bfa0894a79d4 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -54,6 +54,10 @@ tuple_alloc(struct _Py_tuple_state *state, Py_ssize_t size)
return NULL;
}
#if PyTuple_MAXSAVESIZE > 0
+#ifdef Py_DEBUG
+ // tuple_alloc() must not be called after _PyTuple_Fini()
+ assert(state->numfree[0] != -1);
+#endif
if (size < PyTuple_MAXSAVESIZE && (op = state->free_list[size]) != NULL) {
assert(size != 0);
state->free_list[size] = (PyTupleObject *) op->ob_item[0];
@@ -102,6 +106,10 @@ PyTuple_New(Py_ssize_t size)
}
#if PyTuple_MAXSAVESIZE > 0
if (size == 0) {
+#ifdef Py_DEBUG
+ // PyTuple_New() must not be called after _PyTuple_Fini()
+ assert(state->numfree[0] != -1);
+#endif
state->free_list[0] = op;
++state->numfree[0];
Py_INCREF(op); /* extra INCREF so that this is never freed */
@@ -227,6 +235,10 @@ tupledealloc(PyTupleObject *op)
#if PyTuple_MAXSAVESIZE > 0
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_tuple_state *state = &interp->tuple;
+#ifdef Py_DEBUG
+ // tupledealloc() must not be called after _PyTuple_Fini()
+ assert(state->numfree[0] != -1);
+#endif
if (len < PyTuple_MAXSAVESIZE &&
state->numfree[len] < PyTuple_MAXFREELIST &&
Py_IS_TYPE(op, &PyTuple_Type))
@@ -984,6 +996,9 @@ _PyTuple_Fini(PyThreadState *tstate)
Py_CLEAR(state->free_list[0]);
_PyTuple_ClearFreeList(tstate);
+#ifdef Py_DEBUG
+ state->numfree[0] = -1;
+#endif
#endif
}
diff --git a/Python/context.c b/Python/context.c
index 3cf8db4c90cdf..dedbca99384c7 100644
--- a/Python/context.c
+++ b/Python/context.c
@@ -335,6 +335,10 @@ _context_alloc(void)
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_context_state *state = &interp->context;
PyContext *ctx;
+#ifdef Py_DEBUG
+ // _context_alloc() must not be called after _PyContext_Fini()
+ assert(state->numfree != -1);
+#endif
if (state->numfree) {
state->numfree--;
ctx = state->freelist;
@@ -460,6 +464,10 @@ context_tp_dealloc(PyContext *self)
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_context_state *state = &interp->context;
+#ifdef Py_DEBUG
+ // _context_alloc() must not be called after _PyContext_Fini()
+ assert(state->numfree != -1);
+#endif
if (state->numfree < CONTEXT_FREELIST_MAXLEN) {
state->numfree++;
self->ctx_weakreflist = (PyObject *)state->freelist;
@@ -1290,6 +1298,10 @@ _PyContext_Fini(PyThreadState *tstate)
{
Py_CLEAR(_token_missing);
_PyContext_ClearFreeList(tstate);
+#ifdef Py_DEBUG
+ struct _Py_context_state *state = &tstate->interp->context;
+ state->numfree = -1;
+#endif
_PyHamt_Fini();
}
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