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[3.14] gh-135371: Clean tags from pointers in all cases in remote debugging module (GH-135534) #135545

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Merged
merged 1 commit into from
Jun 15, 2025
Merged

[3.14] gh-135371: Clean tags from pointers in all cases in remote debugging module (GH-135534) #135545

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106 changes: 60 additions & 46 deletions Modules/_remote_debugging_module.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@
* ============================================================================ */

#define GET_MEMBER(type, obj, offset) (*(type*)((char*)(obj) + (offset)))
#define CLEAR_PTR_TAG(ptr) (((uintptr_t)(ptr) & ~Py_TAG_BITS))
#define GET_MEMBER_NO_TAG(type, obj, offset) (type)(CLEAR_PTR_TAG(*(type*)((char*)(obj) + (offset))))

/* Size macros for opaque buffers */
#define SIZEOF_BYTES_OBJ sizeof(PyBytesObject)
Expand Down Expand Up @@ -243,6 +245,13 @@ module _remote_debugging
* FORWARD DECLARATIONS
* ============================================================================ */

static inline int
is_frame_valid(
RemoteUnwinderObject *unwinder,
uintptr_t frame_addr,
uintptr_t code_object_addr
);

static int
parse_tasks_in_set(
RemoteUnwinderObject *unwinder,
Expand Down Expand Up @@ -734,8 +743,7 @@ parse_task_name(
return NULL;
}

uintptr_t task_name_addr = GET_MEMBER(uintptr_t, task_obj, unwinder->async_debug_offsets.asyncio_task_object.task_name);
task_name_addr &= ~Py_TAG_BITS;
uintptr_t task_name_addr = GET_MEMBER_NO_TAG(uintptr_t, task_obj, unwinder->async_debug_offsets.asyncio_task_object.task_name);

// The task name can be a long or a string so we need to check the type
char task_name_obj[SIZEOF_PYOBJECT];
Expand Down Expand Up @@ -798,8 +806,7 @@ static int parse_task_awaited_by(
return -1;
}

uintptr_t task_ab_addr = GET_MEMBER(uintptr_t, task_obj, unwinder->async_debug_offsets.asyncio_task_object.task_awaited_by);
task_ab_addr &= ~Py_TAG_BITS;
uintptr_t task_ab_addr = GET_MEMBER_NO_TAG(uintptr_t, task_obj, unwinder->async_debug_offsets.asyncio_task_object.task_awaited_by);

if ((void*)task_ab_addr == NULL) {
return 0;
Expand Down Expand Up @@ -849,8 +856,7 @@ handle_yield_from_frame(
return -1;
}

uintptr_t stackpointer_addr = GET_MEMBER(uintptr_t, iframe, unwinder->debug_offsets.interpreter_frame.stackpointer);
stackpointer_addr &= ~Py_TAG_BITS;
uintptr_t stackpointer_addr = GET_MEMBER_NO_TAG(uintptr_t, iframe, unwinder->debug_offsets.interpreter_frame.stackpointer);

if ((void*)stackpointer_addr != NULL) {
uintptr_t gi_await_addr;
Expand Down Expand Up @@ -917,6 +923,11 @@ parse_coro_chain(
return -1;
}

int8_t frame_state = GET_MEMBER(int8_t, gen_object, unwinder->debug_offsets.gen_object.gi_frame_state);
if (frame_state == FRAME_CLEARED) {
return 0;
}

uintptr_t gen_type_addr = GET_MEMBER(uintptr_t, gen_object, unwinder->debug_offsets.pyobject.ob_type);

PyObject* name = NULL;
Expand All @@ -936,7 +947,7 @@ parse_coro_chain(
}
Py_DECREF(name);

if (GET_MEMBER(int8_t, gen_object, unwinder->debug_offsets.gen_object.gi_frame_state) == FRAME_SUSPENDED_YIELD_FROM) {
if (frame_state == FRAME_SUSPENDED_YIELD_FROM) {
return handle_yield_from_frame(unwinder, gi_iframe_addr, gen_type_addr, render_to);
}

Expand Down Expand Up @@ -981,8 +992,7 @@ create_task_result(
goto error;
}

coro_addr = GET_MEMBER(uintptr_t, task_obj, unwinder->async_debug_offsets.asyncio_task_object.task_coro);
coro_addr &= ~Py_TAG_BITS;
coro_addr = GET_MEMBER_NO_TAG(uintptr_t, task_obj, unwinder->async_debug_offsets.asyncio_task_object.task_coro);

if ((void*)coro_addr != NULL) {
if (parse_coro_chain(unwinder, coro_addr, call_stack) < 0) {
Expand Down Expand Up @@ -1816,10 +1826,10 @@ parse_frame_from_chunks(

char *frame = (char *)frame_ptr;
*previous_frame = GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.previous);

if (GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) >= FRAME_OWNED_BY_INTERPRETER ||
!GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.executable)) {
return 0;
uintptr_t code_object = GET_MEMBER_NO_TAG(uintptr_t, frame_ptr, unwinder->debug_offsets.interpreter_frame.executable);
int frame_valid = is_frame_valid(unwinder, (uintptr_t)frame, code_object);
if (frame_valid != 1) {
return frame_valid;
}

uintptr_t instruction_pointer = GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.instr_ptr);
Expand All @@ -1832,9 +1842,7 @@ parse_frame_from_chunks(
}
#endif

return parse_code_object(
unwinder, result, GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.executable),
instruction_pointer, previous_frame, tlbc_index);
return parse_code_object(unwinder, result, code_object, instruction_pointer, previous_frame, tlbc_index);
}

/* ============================================================================
Expand Down Expand Up @@ -2077,6 +2085,33 @@ find_running_task_and_coro(
* FRAME PARSING FUNCTIONS
* ============================================================================ */

static inline int
is_frame_valid(
RemoteUnwinderObject *unwinder,
uintptr_t frame_addr,
uintptr_t code_object_addr
) {
if ((void*)code_object_addr == NULL) {
return 0;
}

void* frame = (void*)frame_addr;

if (GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) == FRAME_OWNED_BY_CSTACK ||
GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) == FRAME_OWNED_BY_INTERPRETER) {
return 0; // C frame
}

if (GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) != FRAME_OWNED_BY_GENERATOR
&& GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) != FRAME_OWNED_BY_THREAD) {
PyErr_Format(PyExc_RuntimeError, "Unhandled frame owner %d.\n",
GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner));
set_exception_cause(unwinder, PyExc_RuntimeError, "Unhandled frame owner type in async frame");
return -1;
}
return 1;
}

static int
parse_frame_object(
RemoteUnwinderObject *unwinder,
Expand All @@ -2098,13 +2133,10 @@ parse_frame_object(
}

*previous_frame = GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.previous);

if (GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) >= FRAME_OWNED_BY_INTERPRETER) {
return 0;
}

if ((void*)GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.executable) == NULL) {
return 0;
uintptr_t code_object = GET_MEMBER_NO_TAG(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.executable);
int frame_valid = is_frame_valid(unwinder, (uintptr_t)frame, code_object);
if (frame_valid != 1) {
return frame_valid;
}

uintptr_t instruction_pointer = GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.instr_ptr);
Expand All @@ -2117,9 +2149,7 @@ parse_frame_object(
}
#endif

return parse_code_object(
unwinder, result, GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.executable),
instruction_pointer, previous_frame, tlbc_index);
return parse_code_object(unwinder, result, code_object,instruction_pointer, previous_frame, tlbc_index);
}

static int
Expand All @@ -2144,26 +2174,10 @@ parse_async_frame_object(
}

*previous_frame = GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.previous);

*code_object = GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.executable);
// Strip tag bits for consistent comparison
*code_object &= ~Py_TAG_BITS;
assert(code_object != NULL);
if ((void*)*code_object == NULL) {
return 0;
}

if (GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) == FRAME_OWNED_BY_CSTACK ||
GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) == FRAME_OWNED_BY_INTERPRETER) {
return 0; // C frame
}

if (GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) != FRAME_OWNED_BY_GENERATOR
&& GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) != FRAME_OWNED_BY_THREAD) {
PyErr_Format(PyExc_RuntimeError, "Unhandled frame owner %d.\n",
GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner));
set_exception_cause(unwinder, PyExc_RuntimeError, "Unhandled frame owner type in async frame");
return -1;
*code_object = GET_MEMBER_NO_TAG(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.executable);
int frame_valid = is_frame_valid(unwinder, (uintptr_t)frame, *code_object);
if (frame_valid != 1) {
return frame_valid;
}

uintptr_t instruction_pointer = GET_MEMBER(uintptr_t, frame, unwinder->debug_offsets.interpreter_frame.instr_ptr);
Expand Down
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