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[3.14] gh-144563: Fix remote debugging with duplicate libpython mappings from ctypes (GH-144595) (#144655)

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Bartosz Sławecki 2026-02-10 15:31:49 +01:00 • committed by GitHub
parent 8b4210c30e
commit 616e611844
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4 changed files with 95 additions and 14 deletions
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59
Python/remote_debug.h
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@ -133,6 +133,31 @@ typedef struct {
Py_ssize_t page_size;
} proc_handle_t;
// Forward declaration for use in validation function
static int
_Py_RemoteDebug_ReadRemoteMemory(proc_handle_t *handle, uintptr_t remote_address, size_t len, void* dst);
// Optional callback to validate a candidate section address found during
// memory map searches. Returns 1 if the address is valid, 0 to skip it.
// This allows callers to filter out duplicate/stale mappings (e.g. from
// ctypes dlopen) whose sections were never initialized.
typedef int (*section_validator_t)(proc_handle_t *handle, uintptr_t address);
// Validate that a candidate address starts with _Py_Debug_Cookie.
static int
_Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
{
if (address == 0) {
return 0;
}
char buf[sizeof(_Py_Debug_Cookie) - 1];
if (_Py_RemoteDebug_ReadRemoteMemory(handle, address, sizeof(buf), buf) != 0) {
PyErr_Clear();
return 0;
}
return memcmp(buf, _Py_Debug_Cookie, sizeof(buf)) == 0;
}
static void
_Py_RemoteDebug_FreePageCache(proc_handle_t *handle)
{
@ -490,7 +515,8 @@ pid_to_task(pid_t pid)
}
static uintptr_t
search_map_for_section(proc_handle_t *handle, const char* secname, const char* substr) {
search_map_for_section(proc_handle_t *handle, const char* secname, const char* substr,
section_validator_t validator) {
mach_vm_address_t address = 0;
mach_vm_size_t size = 0;
mach_msg_type_number_t count = sizeof(vm_region_basic_info_data_64_t);
@ -542,7 +568,9 @@ search_map_for_section(proc_handle_t *handle, const char* secname, const char* s
if (strncmp(filename, substr, strlen(substr)) == 0) {
uintptr_t result = search_section_in_file(
secname, map_filename, address, size, proc_ref);
if (result != 0) {
if (result != 0
&& (validator == NULL || validator(handle, result)))
{
return result;
}
}
@ -659,7 +687,8 @@ search_elf_file_for_section(
}
static uintptr_t
search_linux_map_for_section(proc_handle_t *handle, const char* secname, const char* substr)
search_linux_map_for_section(proc_handle_t *handle, const char* secname, const char* substr,
section_validator_t validator)
{
char maps_file_path[64];
sprintf(maps_file_path, "/proc/%d/maps", handle->pid);
@ -734,9 +763,12 @@ search_linux_map_for_section(proc_handle_t *handle, const char* secname, const c
if (strstr(filename, substr)) {
retval = search_elf_file_for_section(handle, secname, start, path);
if (retval) {
if (retval
&& (validator == NULL || validator(handle, retval)))
{
break;
}
retval = 0;
}
}
@ -832,7 +864,8 @@ static void* analyze_pe(const wchar_t* mod_path, BYTE* remote_base, const char*
static uintptr_t
search_windows_map_for_section(proc_handle_t* handle, const char* secname, const wchar_t* substr) {
search_windows_map_for_section(proc_handle_t* handle, const char* secname, const wchar_t* substr,
section_validator_t validator) {
HANDLE hProcSnap;
do {
hProcSnap = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, handle->pid);
@ -855,8 +888,11 @@ search_windows_map_for_section(proc_handle_t* handle, const char* secname, const
for (BOOL hasModule = Module32FirstW(hProcSnap, &moduleEntry); hasModule; hasModule = Module32NextW(hProcSnap, &moduleEntry)) {
// Look for either python executable or DLL
if (wcsstr(moduleEntry.szModule, substr)) {
runtime_addr = analyze_pe(moduleEntry.szExePath, moduleEntry.modBaseAddr, secname);
if (runtime_addr != NULL) {
void *candidate = analyze_pe(moduleEntry.szExePath, moduleEntry.modBaseAddr, secname);
if (candidate != NULL
&& (validator == NULL || validator(handle, (uintptr_t)candidate)))
{
runtime_addr = candidate;
break;
}
}
@ -877,7 +913,8 @@ _Py_RemoteDebug_GetPyRuntimeAddress(proc_handle_t* handle)
#ifdef MS_WINDOWS
// On Windows, search for 'python' in executable or DLL
address = search_windows_map_for_section(handle, "PyRuntime", L"python");
address = search_windows_map_for_section(handle, "PyRuntime", L"python",
_Py_RemoteDebug_ValidatePyRuntimeCookie);
if (address == 0) {
// Error out: 'python' substring covers both executable and DLL
PyObject *exc = PyErr_GetRaisedException();
@ -888,7 +925,8 @@ _Py_RemoteDebug_GetPyRuntimeAddress(proc_handle_t* handle)
}
#elif defined(__linux__)
// On Linux, search for 'python' in executable or DLL
address = search_linux_map_for_section(handle, "PyRuntime", "python");
address = search_linux_map_for_section(handle, "PyRuntime", "python",
_Py_RemoteDebug_ValidatePyRuntimeCookie);
if (address == 0) {
// Error out: 'python' substring covers both executable and DLL
PyObject *exc = PyErr_GetRaisedException();
@ -902,7 +940,8 @@ _Py_RemoteDebug_GetPyRuntimeAddress(proc_handle_t* handle)
const char* candidates[] = {"libpython", "python", "Python", NULL};
for (const char** candidate = candidates; *candidate; candidate++) {
PyErr_Clear();
address = search_map_for_section(handle, "PyRuntime", *candidate);
address = search_map_for_section(handle, "PyRuntime", *candidate,
_Py_RemoteDebug_ValidatePyRuntimeCookie);
if (address != 0) {
break;
}