Commit 1bfdcf9057 for openssl.org

commit 1bfdcf90577f4474537da6b21474c02594f5868c
Author: Neil Horman <nhorman@openssl.org>
Date:   Mon Dec 15 08:43:32 2025 -0500

    Prevent freeing of parent listener in SSL_listen_ex

    Its been reported that, when using SSL_listen_ex to obtain a new
    connection from a listener, that, if the listener is freed prior to the
    obtained connection, we get use-after-free conditions when freeing said
    obtained connections.

    This occurs because SSL_listen_ex fails to take a reference on the
    parent listener SSL object (in the same way that SSL_new_from_listener
    does).  If the listener is freed first, then several listener resources
    are freed, which the obtained connection still makes use of, hence the
    use-after-free.

    The fix is to do what SSL_new_from_listener does, namely:
    1) Increase the reference count on the listener SSL object.
    2) Ensure that the connection qc->listener points to the listener object
       so that, when the connection is freed, we call SSL_free on the
       listener object, dropping the reference count we take in
       SSL_listen_ex.

    While we're at it, this PR also modifies the quicapi test for testing
    the SSL_listen_ex call, freeing the listener first to ensure that the
    increased refcount holds the SSL object data stable until the connection
    is freed.

    Thanks to Stanislav Fort at Asile Research for pointing out this issue.

    fixes openssl/project#1766

    Reviewed-by: Saša Nedvědický <sashan@openssl.org>
    Reviewed-by: Matt Caswell <matt@openssl.org>
    (Merged from https://github.com/openssl/openssl/pull/29398)

diff --git a/ssl/quic/quic_impl.c b/ssl/quic/quic_impl.c
index 53bb247e85..87c1370a8d 100644
--- a/ssl/quic/quic_impl.c
+++ b/ssl/quic/quic_impl.c
@@ -4670,9 +4670,21 @@ int ossl_quic_peeloff_conn(SSL *listener, SSL *new_conn)

         qc = cctx.qc;
         ql = lctx.ql;
+        /*
+         * Need to ensure that we take a reference on our new listener
+         * so that we don't free it before this connection
+         */
+        if (!SSL_up_ref(&ql->obj.ssl))
+            goto out;
+
         ossl_quic_channel_free(qc->ch);
         ossl_quic_port_free(qc->port);
         ossl_quic_engine_free(qc->engine);
+        /*
+         * Ensure that we point to our listener so we can drop
+         * the above refcount when this SSL object is freed
+         */
+        qc->listener = ql;
         qc->obj.engine = ql->engine;
         qc->engine = ql->engine;
         qc->port = ql->port;
diff --git a/test/quicapitest.c b/test/quicapitest.c
index 26d80d1a4b..d311ec65da 100644
--- a/test/quicapitest.c
+++ b/test/quicapitest.c
@@ -2910,9 +2910,9 @@ static int test_ssl_listen_ex(void)
     testresult = 1;

 err:
+    SSL_free(qlistener);
     SSL_free(serverssl);
     SSL_free(clientssl);
-    SSL_free(qlistener);
     SSL_CTX_free(sctx);
     SSL_CTX_free(cctx);
     SSL_CTX_free(qmctx);