From: Gregory P. Smith <greg@krypto.org>
Date: Thu, 28 Mar 2024 10:11:58 +0000 (-0700)
Subject: gh-117310: Remove extra DECREF on "no ciphers" error path in `_ssl._SSLContext` const... 
X-Git-Tag: v3.13.0a6~128
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8cb7d7ff86a1a2d41195f01ba4f218941dd7308c;p=thirdparty%2FPython%2Fcpython.git

gh-117310: Remove extra DECREF on "no ciphers" error path in `_ssl._SSLContext` constructor (#117309)

Remove extra self DECREF on ssl "no ciphers" error path.

This doesn't come up in practice because nobody links against a broken
OpenSSL library that provides nothing.
---

diff --git a/Misc/NEWS.d/next/Library/2024-03-27-21-05-52.gh-issue-117310.Bt2wox.rst b/Misc/NEWS.d/next/Library/2024-03-27-21-05-52.gh-issue-117310.Bt2wox.rst
new file mode 100644
index 000000000000..429b890b8b60
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-03-27-21-05-52.gh-issue-117310.Bt2wox.rst
@@ -0,0 +1,4 @@
+Fixed an unlikely early & extra ``Py_DECREF`` triggered crash in :mod:`ssl`
+when creating a new ``_ssl._SSLContext`` if CPython was built implausibly such
+that the default cipher list is empty **or** the SSL library it was linked
+against reports a failure from its C ``SSL_CTX_set_cipher_list()`` API.
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index f5a79dcb1ac5..fbf914c43219 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -3166,7 +3166,6 @@ _ssl__SSLContext_impl(PyTypeObject *type, int proto_version)
         result = SSL_CTX_set_cipher_list(ctx, "HIGH:!aNULL:!eNULL");
     }
     if (result == 0) {
-        Py_DECREF(self);
         ERR_clear_error();
         PyErr_SetString(get_state_ctx(self)->PySSLErrorObject,
                         "No cipher can be selected.");