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gh-133157: remove usage of _Py_NO_SANITIZE_UNDEFINED in faulthandler (#134047)

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In `faulthandler_sigfpe()`, instead of using 1/0 arithmetic, we explicitly raise SIGFPE.
We also remove `faulthandler._read_null()` since reading from NULL is an undefined
behavior and `faulthandler` should not check for low-level C undefined behaviors.
This commit is contained in:
Bénédikt Tran 2025-05-18 10:16:10 +02:00 • committed by GitHub
parent 22e4a40d90
commit 0a160bf14c
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2 changed files with 2 additions and 52 deletions
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23
Lib/test/test_faulthandler.py
View file

@ -166,29 +166,6 @@ class FaultHandlerTests(unittest.TestCase):
fatal_error = 'Windows fatal exception: %s' % name_regex
self.check_error(code, line_number, fatal_error, **kw)
@unittest.skipIf(sys.platform.startswith('aix'),
"the first page of memory is a mapped read-only on AIX")
def test_read_null(self):
if not MS_WINDOWS:
self.check_fatal_error("""
import faulthandler
faulthandler.enable()
faulthandler._read_null()
""",
3,
# Issue #12700: Read NULL raises SIGILL on Mac OS X Lion
'(?:Segmentation fault'
'|Bus error'
'|Illegal instruction)')
else:
self.check_windows_exception("""
import faulthandler
faulthandler.enable()
faulthandler._read_null()
""",
3,
'access violation')
@skip_segfault_on_android
def test_sigsegv(self):
self.check_fatal_error("""

31
Modules/faulthandler.c
View file

@ -1069,18 +1069,6 @@ faulthandler_suppress_crash_report(void)
#endif
}
static PyObject* _Py_NO_SANITIZE_UNDEFINED
faulthandler_read_null(PyObject *self, PyObject *args)
{
volatile int *x;
volatile int y;
faulthandler_suppress_crash_report();
x = NULL;
y = *x;
return PyLong_FromLong(y);
}
static void
faulthandler_raise_sigsegv(void)
@ -1158,23 +1146,12 @@ faulthandler_fatal_error_c_thread(PyObject *self, PyObject *args)
Py_RETURN_NONE;
}
static PyObject* _Py_NO_SANITIZE_UNDEFINED
static PyObject*
faulthandler_sigfpe(PyObject *self, PyObject *Py_UNUSED(dummy))
{
faulthandler_suppress_crash_report();
/* Do an integer division by zero: raise a SIGFPE on Intel CPU, but not on
PowerPC. Use volatile to disable compile-time optimizations. */
volatile int x = 1, y = 0, z;
z = x / y;
/* If the division by zero didn't raise a SIGFPE (e.g. on PowerPC),
raise it manually. */
raise(SIGFPE);
/* This line is never reached, but we pretend to make something with z
to silence a compiler warning. */
return PyLong_FromLong(z);
Py_UNREACHABLE();
}
static PyObject *
@ -1316,10 +1293,6 @@ static PyMethodDef module_methods[] = {
"Unregister the handler of the signal "
"'signum' registered by register().")},
#endif
{"_read_null", faulthandler_read_null, METH_NOARGS,
PyDoc_STR("_read_null($module, /)\n--\n\n"
"Read from NULL, raise "
"a SIGSEGV or SIGBUS signal depending on the platform.")},
{"_sigsegv", faulthandler_sigsegv, METH_VARARGS,
PyDoc_STR("_sigsegv($module, release_gil=False, /)\n--\n\n"
"Raise a SIGSEGV signal.")},