This doesn't happen naturally, but is allowed by the ASDL and compiler.
We don't want to change ASDL for backward compatibility reasons
(GH-57645, GH-92987)
(cherry picked from commit 200c9a8da0)
Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
Converting a large enough `int` to a decimal string raises `ValueError` as expected. However, the raise comes _after_ the quadratic-time base-conversion algorithm has run to completion. For effective DOS prevention, we need some kind of check before entering the quadratic-time loop. Oops! =)
The quick fix: essentially we catch _most_ values that exceed the threshold up front. Those that slip through will still be on the small side (read: sufficiently fast), and will get caught by the existing check so that the limit remains exact.
The justification for the current check. The C code check is:
```c
max_str_digits / (3 * PyLong_SHIFT) <= (size_a - 11) / 10
```
In GitHub markdown math-speak, writing $M$ for `max_str_digits`, $L$ for `PyLong_SHIFT` and $s$ for `size_a`, that check is:
$$\left\lfloor\frac{M}{3L}\right\rfloor \le \left\lfloor\frac{s - 11}{10}\right\rfloor$$
From this it follows that
$$\frac{M}{3L} < \frac{s-1}{10}$$
hence that
$$\frac{L(s-1)}{M} > \frac{10}{3} > \log_2(10).$$
So
$$2^{L(s-1)} > 10^M.$$
But our input integer $a$ satisfies $|a| \ge 2^{L(s-1)}$, so $|a|$ is larger than $10^M$. This shows that we don't accidentally capture anything _below_ the intended limit in the check.
<!-- gh-issue-number: gh-95778 -->
* Issue: gh-95778
<!-- /gh-issue-number -->
Co-authored-by: Gregory P. Smith [Google LLC] <greg@krypto.org>
(cherry picked from commit b126196838)
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
* gh-68163: Correct conversion of Rational instances to float
Also document that numerator/denominator properties are instances of Integral.
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
(cherry picked from commit 8464b754c4)
Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
Integer to and from text conversions via CPython's bignum `int` type is not safe against denial of service attacks due to malicious input. Very large input strings with hundred thousands of digits can consume several CPU seconds.
This PR comes fresh from a pile of work done in our private PSRT security response team repo.
This backports https://github.com/python/cpython/pull/96499 aka 511ca94520
Signed-off-by: Christian Heimes [Red Hat] <christian@python.org>
Tons-of-polishing-up-by: Gregory P. Smith [Google] <greg@krypto.org>
Reviews via the private PSRT repo via many others (see the NEWS entry in the PR).
<!-- gh-issue-number: gh-95778 -->
* Issue: gh-95778
<!-- /gh-issue-number -->
I wrote up [a one pager for the release managers](https://docs.google.com/document/d/1KjuF_aXlzPUxTK4BMgezGJ2Pn7uevfX7g0_mvgHlL7Y/edit#).
If kernel fips is enabled, we get permission error upon doing
`import crypt`. So, if kernel fips is enabled, disable the
unallowed hashing methods.
Python 3.9.1 (default, May 10 2022, 11:36:26)
[GCC 10.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import crypt
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python3.9/crypt.py", line 117, in <module>
_add_method('MD5', '1', 8, 34)
File "/usr/lib/python3.9/crypt.py", line 94, in _add_method
result = crypt('', salt)
File "/usr/lib/python3.9/crypt.py", line 82, in crypt
return _crypt.crypt(word, salt)
PermissionError: [Errno 1] Operation not permitted
Signed-off-by: Shreenidhi Shedi <sshedi@vmware.com>
(cherry picked from commit 2fa03b1b07)
Co-authored-by: Shreenidhi Shedi <53473811+sshedi@users.noreply.github.com>
As a consequence of the added test, this commit also includes
fixes for broken examples.
- Add separate namespace for trace tests bco. module level callback
- Move more backup and cursor examples under separate namespaces.
(cherry picked from commit bf9259776d)
Co-authored-by: Erlend E. Aasland <erlend.aasland@protonmail.com>
Tests for IsolatedAsyncioTestCase.debug() rely on the runner be closed
in __del__. It makes tests depending on the GC an unreliable on other
implementations. It is better to tear down the loop explicitly even if
currently there is no a public API for this.
(cherry picked from commit 4de06e3cc0)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
find_unused_port() has an inherent race condition, but we can't use
bind_port() as that uses .getsockname() which this test is exercising.
Try binding to unused ports a few times before failing.
Signed-off-by: Ross Burton <ross.burton@arm.com>
(cherry picked from commit df11012697)
Co-authored-by: Ross Burton <ross.burton@arm.com>
The `movies[bisect(movies, 1960, key=by_year)]` will actually return only movies **after** 1960.
(cherry picked from commit 4317b25a23)
Co-authored-by: prego <pedropregueiro@gmail.com>
