pycryptodome-3.15.0 fails test test_negate (Crypto.SelfTest.PublicKey.test_ECC_25519.TestEccPoint_Ed25519)

[PPed72]

Originally reported in Gentoo Linux Bugzilla: https://bugs.gentoo.org/861206

======================================================================
FAIL: test_negate (Crypto.SelfTest.PublicKey.test_ECC_25519.TestEccPoint_Ed25519)

Traceback (most recent call last):
File "/var/tmp/portage/dev-python/pycryptodome-3.15.0/work/pycryptodome-3.15.0-python3_10/install/usr/lib/python3.10/site-packages/Crypto/SelfTest/PublicKey/test_ECC_25519.py", line 114, in test_negate
self.failUnless(sum.is_point_at_infinity())
AssertionError: False is not true

---

Ran 7213 tests in 28.050s

FAILED (failures=1)
Traceback (most recent call last):
File "", line 3, in
File "/var/tmp/portage/dev-python/pycryptodome-3.15.0/work/pycryptodome-3.15.0-python3_10/install/usr/lib/python3.10/site-packages/Crypto/SelfTest/init.py", line 77, in run
raise SelfTestError("Self-test failed", result)
Crypto.SelfTest.SelfTestError: ('Self-test failed', <unittest.runner.TextTestResult run=7213 errors=0 failures=1>)

• ERROR: dev-python/pycryptodome-3.15.0::gentoo failed (test phase):
• (no error message)

[ivan]

I saw this on NixOS master as well after compiling everything with -march=haswell -mtune=haswell / gcc 11.3.0. I tried to reproduce on Debian 11.5 (gcc (Debian 10.2.1-6) 10.2.1 20210110) by compiling just Python 3.10.7 and pycryptodome with -march=haswell -mtune=haswell, but I could not; the tests passed.

[ivan]

Oh, -march=haswell with gcc 11.3.0 does cause this test to fail; here are some repro instructions for Debian sid / unstable:

apt update
apt install wget ca-certificates git build-essential gcc-11 libssl-dev zlib1g-dev libbz2-dev libsqlite3-dev libxml2-dev libxslt1-dev libreadline-dev libffi-dev pkg-config

non-root:

wget https://raw.githubusercontent.com/pyenv/pyenv-installer/master/bin/pyenv-installer
chmod +x pyenv-installer
./pyenv-installer
CC=gcc-11 CFLAGS="-march=haswell -mtune=haswell" ~/.pyenv/bin/pyenv install 3.10.7

git clone https://github.com/Legrandin/pycryptodome
cd pycryptodome
CC=gcc-11 CFLAGS="-march=haswell -mtune=haswell" ~/.pyenv/versions/3.10.7/bin/python3 setup.py test

I observe:

....................................................................................................................................................................................
======================================================================
FAIL: test_negate (Crypto.SelfTest.PublicKey.test_ECC_25519.TestEccPoint_Ed25519)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/at/pycryptodome/build/lib.linux-x86_64-cpython-310/Crypto/SelfTest/PublicKey/test_ECC_25519.py", line 114, in test_negate
    self.failUnless(sum.is_point_at_infinity())
AssertionError: False is not true

----------------------------------------------------------------------
Ran 3501 tests in 31.933s

FAILED (failures=1)
Traceback (most recent call last):
  File "/home/at/pycryptodome/setup.py", line 498, in <module>
    setup(
  File "/home/at/.pyenv/versions/3.10.7/lib/python3.10/site-packages/setuptools/__init__.py", line 87, in setup
    return distutils.core.setup(**attrs)
  File "/home/at/.pyenv/versions/3.10.7/lib/python3.10/site-packages/setuptools/_distutils/core.py", line 177, in setup
    return run_commands(dist)
  File "/home/at/.pyenv/versions/3.10.7/lib/python3.10/site-packages/setuptools/_distutils/core.py", line 193, in run_commands
    dist.run_commands()
  File "/home/at/.pyenv/versions/3.10.7/lib/python3.10/site-packages/setuptools/_distutils/dist.py", line 968, in run_commands
    self.run_command(cmd)
  File "/home/at/.pyenv/versions/3.10.7/lib/python3.10/site-packages/setuptools/dist.py", line 1217, in run_command
    super().run_command(command)
  File "/home/at/.pyenv/versions/3.10.7/lib/python3.10/site-packages/setuptools/_distutils/dist.py", line 987, in run_command
    cmd_obj.run()
  File "/home/at/pycryptodome/setup.py", line 189, in run
    SelfTest.run(module=moduleObj, verbosity=self.verbose, stream=sys.stdout, config=self.config)
  File "/home/at/pycryptodome/build/lib.linux-x86_64-cpython-310/Crypto/SelfTest/__init__.py", line 77, in run
    raise SelfTestError("Self-test failed", result)
Crypto.SelfTest.SelfTestError: ('Self-test failed', <unittest.runner.TextTestResult run=3501 errors=0 failures=1>)

# gcc-11 --version
gcc-11 (Debian 11.3.0-6) 11.3.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[SuperSandro2000]

I saw this on NixOS master as well after compiling everything with -march=haswell -mtune=haswell / gcc 11.3.0. I tried to reproduce on Debian 11.5 (gcc (Debian 10.2.1-6) 10.2.1 20210110) by compiling just Python 3.10.7 and pycryptodome with -march=haswell -mtune=haswell, but I could not; the tests passed.

I encountered the same with march skylake.

[Legrandin]

I can confirm I can reproduce it with the combination described by @ivan.

It looks like a compiler bug because the issue disappears if I mark add_25519() with __attribute__((noinline)). However, that is not an acceptable workaround... It also disappears by using uint32_t instead of uint64_t in add_25519() which is an overdue optimization that should have been done in any case, so that it what 1c043ab (also) does.

[SuperSandro2000]

The patch fixes my problem.

[Legrandin]

Fixed in v3.17