python · miss-islington · Mar 3, 2022
diff --git a/Misc/NEWS.d/next/Tests/2022-03-03-17-36-24.bpo-46913.vxETIE.rst b/Misc/NEWS.d/next/Tests/2022-03-03-17-36-24.bpo-46913.vxETIE.rst
@@ -0,0 +1,3 @@
+Fix test_faulthandler.test_sigfpe() if Python is built with undefined
+behavior sanitizer (UBSAN): disable UBSAN on the faulthandler_sigfpe()
+function. Patch by Victor Stinner.
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
@@ -1099,17 +1099,35 @@ faulthandler_fatal_error_c_thread(PyObject *self, PyObject *args)
    Py_RETURN_NONE;
 }

-static PyObject *
+// clang uses __attribute__((no_sanitize("undefined")))
+// GCC 4.9+ uses __attribute__((no_sanitize_undefined))
+#if defined(__has_feature)  // Clang
+#  if __has_feature(undefined_behavior_sanitizer)
+#    define _Py_NO_SANITIZE_UNDEFINED __attribute__((no_sanitize("undefined")))
+#  endif
+#endif
+#if defined(__GNUC__) \
+    && ((__GNUC__ >= 5) || (__GNUC__ == 4) && (__GNUC_MINOR__ >= 9))
+#  define _Py_NO_SANITIZE_UNDEFINED __attribute__((no_sanitize_undefined))
+#endif
+#ifndef _Py_NO_SANITIZE_UNDEFINED
+#  define _Py_NO_SANITIZE_UNDEFINED
+#endif
+
+static PyObject* _Py_NO_SANITIZE_UNDEFINED
 faulthandler_sigfpe(PyObject *self, PyObject *args)
 {
+    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;
-    faulthandler_suppress_crash_report();
    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);