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gh-138122: Don't sample partial frame chains (#141912)

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Pablo Galindo Salgado 2025-12-07 15:53:48 +00:00 • committed by GitHub
parent c5b37228af
commit d6d850df89
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13 changed files with 135 additions and 105 deletions
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30
Modules/_remote_debugging/frames.c
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@ -154,14 +154,13 @@ is_frame_valid(
void* frame = (void*)frame_addr;
if (GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner) == FRAME_OWNED_BY_INTERPRETER) {
return 0; // C frame
char owner = GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner);
if (owner == FRAME_OWNED_BY_INTERPRETER) {
return 0; // C frame or sentinel base 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));
if (owner != FRAME_OWNED_BY_GENERATOR && owner != FRAME_OWNED_BY_THREAD) {
PyErr_Format(PyExc_RuntimeError, "Unhandled frame owner %d.\n", owner);
set_exception_cause(unwinder, PyExc_RuntimeError, "Unhandled frame owner type in async frame");
return -1;
}
@ -260,6 +259,7 @@ process_frame_chain(
uintptr_t initial_frame_addr,
StackChunkList *chunks,
PyObject *frame_info,
uintptr_t base_frame_addr,
uintptr_t gc_frame,
uintptr_t last_profiled_frame,
int *stopped_at_cached_frame,
@ -269,6 +269,7 @@ process_frame_chain(
{
uintptr_t frame_addr = initial_frame_addr;
uintptr_t prev_frame_addr = 0;
uintptr_t last_frame_addr = 0; // Track last frame visited for validation
const size_t MAX_FRAMES = 1024 + 512;
size_t frame_count = 0;
@ -296,6 +297,7 @@ process_frame_chain(
PyObject *frame = NULL;
uintptr_t next_frame_addr = 0;
uintptr_t stackpointer = 0;
last_frame_addr = frame_addr; // Remember this frame address
if (++frame_count > MAX_FRAMES) {
PyErr_SetString(PyExc_RuntimeError, "Too many stack frames (possible infinite loop)");
@ -303,7 +305,6 @@ process_frame_chain(
return -1;
}
// Try chunks first, fallback to direct memory read
if (parse_frame_from_chunks(unwinder, &frame, frame_addr, &next_frame_addr, &stackpointer, chunks) < 0) {
PyErr_Clear();
uintptr_t address_of_code_object = 0;
@ -377,6 +378,17 @@ process_frame_chain(
frame_addr = next_frame_addr;
}
// Validate we reached the base frame (sentinel at bottom of stack)
// Only validate if we walked the full chain (didn't stop at cached frame)
// and base_frame_addr is provided (non-zero)
int stopped_early = stopped_at_cached_frame && *stopped_at_cached_frame;
if (!stopped_early && base_frame_addr != 0 && last_frame_addr != base_frame_addr) {
PyErr_Format(PyExc_RuntimeError,
"Incomplete sample: did not reach base frame (expected 0x%lx, got 0x%lx)",
base_frame_addr, last_frame_addr);
return -1;
}
return 0;
}
@ -540,7 +552,7 @@ collect_frames_with_cache(
Py_ssize_t frames_before = PyList_GET_SIZE(frame_info);
int stopped_at_cached = 0;
if (process_frame_chain(unwinder, frame_addr, chunks, frame_info, gc_frame,
if (process_frame_chain(unwinder, frame_addr, chunks, frame_info, 0, gc_frame,
last_profiled_frame, &stopped_at_cached,
addrs, &num_addrs, FRAME_CACHE_MAX_FRAMES) < 0) {
return -1;
@ -562,7 +574,7 @@ collect_frames_with_cache(
// Cache miss - continue walking from last_profiled_frame to get the rest
STATS_INC(unwinder, frame_cache_misses);
Py_ssize_t frames_before_walk = PyList_GET_SIZE(frame_info);
if (process_frame_chain(unwinder, last_profiled_frame, chunks, frame_info, gc_frame,
if (process_frame_chain(unwinder, last_profiled_frame, chunks, frame_info, 0, gc_frame,
0, NULL, addrs, &num_addrs, FRAME_CACHE_MAX_FRAMES) < 0) {
return -1;
}