[3.10] gh-144833: Fix use-after-free in SSL module when SSL_new() fails (GH-144843...

gh-144833: Fix use-after-free in SSL module when SSL_new() fails (GH-144843)

In newPySSLSocket(), when SSL_new() returns NULL, Py_DECREF(self)
was called before _setSSLError(get_state_ctx(self), ...), causing
a use-after-free. Additionally, get_state_ctx() was called with
self (PySSLSocket*) instead of sslctx (PySSLContext*), which is
a type confusion bug.

Fix by calling _setSSLError() before Py_DECREF() and using
sslctx instead of self for get_state_ctx().
(cherry picked from commit c91638ca0671b8038831f963ed44e66cdda006a2)

Co-authored-by: Ramin Farajpour Cami <ramin.blackhat@gmail.com>

diff --git a/Misc/NEWS.d/next/Library/2026-02-15-00-00-00.gh-issue-144833.TUelo1.rst b/Misc/NEWS.d/next/Library/2026-02-15-00-00-00.gh-issue-144833.TUelo1.rst
new file mode 100644 (file)
index 0000000..6d5b18f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-02-15-00-00-00.gh-issue-144833.TUelo1.rst
@@ -0,0 +1,3 @@
+Fixed a use-after-free in :mod:`ssl` when ``SSL_new()`` returns NULL in
+``newPySSLSocket()``. The error was reported via a dangling pointer after the
+object had already been freed.

diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 6852cc363b8c77381d4e9057b519f4d671641919..3bd8b96dcc4bbc038450c0adee12a104dea3a70e 100644 (file)
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -846,8 +846,8 @@ newPySSLSocket(PySSLContext *sslctx, PySocketSockObject *sock,
     self->ssl = SSL_new(ctx);
     PySSL_END_ALLOW_THREADS
     if (self->ssl == NULL) {
+        _setSSLError(get_state_ctx(sslctx), NULL, 0, __FILE__, __LINE__);
         Py_DECREF(self);
-        _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);
         return NULL;
     }
     /* bpo43522 and OpenSSL < 1.1.1l: copy hostflags manually */