[Python-checkins] bpo-46913: Fix test_faulthandler.test_sigfpe() on UBSAN (GH-31662)

[vstinner]

https://github.com/python/cpython/commit/4173d677a1d7c72bb32d292fbff1b4cf073d615c
commit: 4173d677a1d7c72bb32d292fbff1b4cf073d615c
branch: main
author: Victor Stinner <vstinner at python.org>
committer: vstinner <vstinner at python.org>
date: 2022-03-03T21:45:01+01:00
summary:

bpo-46913: Fix test_faulthandler.test_sigfpe() on UBSAN (GH-31662)

Disable undefined behavior sanitizer (UBSAN) on
faulthandler_sigfpe().

files:
A Misc/NEWS.d/next/Tests/2022-03-03-17-36-24.bpo-46913.vxETIE.rst
M Modules/faulthandler.c

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
new file mode 100644
index 0000000000000..65fed1c249d87
--- /dev/null
+++ 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
index 46e18c17d8d35..4f9f661c662a6 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -1102,17 +1102,35 @@ 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);