gnutls: patch CVE-2025-6395

Pick relevant commit from 3.8.10 release MR [1]. [1] https://gitlab.com/gnutls/gnutls/-/merge_requests/1979 (From OE-Core rev: 14fbbdc51f7d02bc10b8078c0ba1de17f1563d73) Signed-off-by: Peter Marko <peter.marko@siemens.com> Signed-off-by: Steve Sakoman <steve@sakoman.com>
2026-02-10 10:43:02 +01:00 · 2025-07-27 19:49:19 +02:00
parent f569a0f2d9
commit 114eddfaef
2 changed files with 300 additions and 0 deletions
--- a/meta/recipes-support/gnutls/gnutls/CVE-2025-6395.patch
+++ b/meta/recipes-support/gnutls/gnutls/CVE-2025-6395.patch
@@ -0,0 +1,299 @@
+From 23135619773e6ec087ff2abc65405bd4d5676bad Mon Sep 17 00:00:00 2001
+From: Daiki Ueno <ueno@gnu.org>
+Date: Mon, 7 Jul 2025 11:15:45 +0900
+Subject: [PATCH] handshake: clear HSK_PSK_SELECTED is when resetting
+ binders
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+When a TLS 1.3 handshake involves HRR and resumption or PSK, and the
+second Client Hello omits PSK, the server would result in a NULL
+pointer dereference as the PSK binder information is cleared while the
+HSK_PSK_SELECTED flag is still set. This makes sure that
+HSK_PSK_SELECTED flag is always cleared when the PSK binders are
+reset. This also makes it clear the HSK_PSK_SELECTED flag is valid
+only during a handshake; after that, whether PSK is used can be
+checked with gnutls_auth_client_get_type.
+
+Reported by Stefan Bühler.
+
+Signed-off-by: Daiki Ueno <ueno@gnu.org>
+
+CVE: CVE-2025-6395
+Upstream-Status: Backport [https://gitlab.com/gnutls/gnutls/-/commit/23135619773e6ec087ff2abc65405bd4d5676bad]
+Signed-off-by: Peter Marko <peter.marko@siemens.com>
+---
+ NEWS                                  |   4 +
+ lib/handshake.c                       |  25 +++-
+ lib/state.c                           |   4 +-
+ tests/Makefile.am                     |   2 +
+ tests/tls13/hello_retry_request_psk.c | 173 ++++++++++++++++++++++++++
+ 5 files changed, 204 insertions(+), 4 deletions(-)
+ create mode 100644 tests/tls13/hello_retry_request_psk.c
+
+diff --git a/NEWS b/NEWS
+index 1334516c6..d800e83b0 100644
+--- a/NEWS
+++ b/NEWS
+@@ -5,6 +5,10 @@ Copyright (C) 2000-2016 Free Software Foundation, Inc.
+ Copyright (C) 2013-2019 Nikos Mavrogiannopoulos
+ See the end for copying conditions.
+ 
+** libgnutls: Fix NULL pointer dereference when 2nd Client Hello omits PSK
+   Reported by Stefan Bühler. [GNUTLS-SA-2025-07-07-4, CVSS: medium]
+   [CVE-2025-6395]
+
+ ** libgnutls: Fix heap read buffer overrun in parsing X.509 SCTS timestamps
+    Spotted by oss-fuzz and reported by OpenAI Security Research Team,
+    and fix developed by Andrew Hamilton. [GNUTLS-SA-2025-07-07-1,
+diff --git a/lib/handshake.c b/lib/handshake.c
+index 722307be7..489d02194 100644
+--- a/lib/handshake.c
+++ b/lib/handshake.c
+@@ -589,9 +589,28 @@ static int set_auth_types(gnutls_session_t session)
+ 		/* Under TLS1.3 this returns a KX which matches the negotiated
+ 		 * groups from the key shares; if we are resuming then the KX seen
+ 		 * here doesn't match the original session. */
+-		if (!session->internals.resumed)
+-			kx = gnutls_kx_get(session);
+-		else
+		if (!session->internals.resumed) {
+			const gnutls_group_entry_st *group = get_group(session);
+
+			if (session->internals.hsk_flags & HSK_PSK_SELECTED) {
+				if (group) {
+					kx = group->pk == GNUTLS_PK_DH ?
+						     GNUTLS_KX_DHE_PSK :
+						     GNUTLS_KX_ECDHE_PSK;
+				} else {
+					kx = GNUTLS_KX_PSK;
+				}
+			} else if (group) {
+				/* Not necessarily be RSA, but just to
+				 * make _gnutls_map_kx_get_cred below
+				 * work.
+				 */
+				kx = group->pk == GNUTLS_PK_DH ?
+					     GNUTLS_KX_DHE_RSA :
+					     GNUTLS_KX_ECDHE_RSA;
+			} else
+				kx = GNUTLS_KX_UNKNOWN;
+		} else
+ 			kx = GNUTLS_KX_UNKNOWN;
+ 	} else {
+ 		/* TLS1.2 or earlier, kx is associated with ciphersuite */
+diff --git a/lib/state.c b/lib/state.c
+index ec514c0cd..10ec0eadb 100644
+--- a/lib/state.c
+++ b/lib/state.c
+@@ -202,7 +202,8 @@ gnutls_kx_algorithm_t gnutls_kx_get(gnutls_session_t session)
+ 		const gnutls_group_entry_st *group = get_group(session);
+ 
+ 		if (ver->tls13_sem) {
+-			if (session->internals.hsk_flags & HSK_PSK_SELECTED) {
+			if (gnutls_auth_client_get_type(session) ==
+			    GNUTLS_CRD_PSK) {
+ 				if (group) {
+ 					if (group->pk == GNUTLS_PK_DH)
+ 						return GNUTLS_KX_DHE_PSK;
+@@ -349,6 +350,7 @@ void reset_binders(gnutls_session_t session)
+ 	_gnutls_free_temp_key_datum(&session->key.binders[0].psk);
+ 	_gnutls_free_temp_key_datum(&session->key.binders[1].psk);
+ 	memset(session->key.binders, 0, sizeof(session->key.binders));
+	session->internals.hsk_flags &= ~HSK_PSK_SELECTED;
+ }
+ 
+ /* Check whether certificate credentials of type @cert_type are set
+diff --git a/tests/Makefile.am b/tests/Makefile.am
+index c2d226a00..e43faf10f 100644
+--- a/tests/Makefile.am
+++ b/tests/Makefile.am
+@@ -128,6 +128,8 @@ ctests += tls13/hello_retry_request
+ 
+ ctests += tls13/hello_retry_request_resume
+ 
+ctests += tls13/hello_retry_request_psk
+
+ ctests += tls13/psk-ext
+ 
+ ctests += tls13/key_update
+diff --git a/tests/tls13/hello_retry_request_psk.c b/tests/tls13/hello_retry_request_psk.c
+new file mode 100644
+index 000000000..a20cb0d96
+--- /dev/null
+++ b/tests/tls13/hello_retry_request_psk.c
+@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2017-2025 Red Hat, Inc.
+ *
+ * Author: Nikos Mavrogiannopoulos, Daiki Ueno
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include <string.h>
+#include <gnutls/gnutls.h>
+#include <assert.h>
+
+#include "cert-common.h"
+#include "utils.h"
+#include "tls13/ext-parse.h"
+#include "eagain-common.h"
+
+/* This program exercises the case where a TLS 1.3 handshake ends up
+ * with HRR, and the first CH includes PSK while the 2nd CH omits
+ * it */
+
+const char *testname = "hello entry request";
+
+const char *side = "";
+
+#define myfail(fmt, ...) fail("%s: " fmt, testname, ##__VA_ARGS__)
+
+static void tls_log_func(int level, const char *str)
+{
+	fprintf(stderr, "%s|<%d>| %s", side, level, str);
+}
+
+struct ctx_st {
+	unsigned hrr_seen;
+	unsigned hello_counter;
+};
+
+static int pskfunc(gnutls_session_t session, const char *username,
+		   gnutls_datum_t *key)
+{
+	if (debug)
+		printf("psk: username %s\n", username);
+	key->data = gnutls_malloc(4);
+	key->data[0] = 0xDE;
+	key->data[1] = 0xAD;
+	key->data[2] = 0xBE;
+	key->data[3] = 0xEF;
+	key->size = 4;
+	return 0;
+}
+
+static int hello_callback(gnutls_session_t session, unsigned int htype,
+			  unsigned post, unsigned int incoming,
+			  const gnutls_datum_t *msg)
+{
+	struct ctx_st *ctx = gnutls_session_get_ptr(session);
+	assert(ctx != NULL);
+
+	if (htype == GNUTLS_HANDSHAKE_HELLO_RETRY_REQUEST)
+		ctx->hrr_seen = 1;
+
+	if (htype == GNUTLS_HANDSHAKE_CLIENT_HELLO) {
+		if (post == GNUTLS_HOOK_POST)
+			ctx->hello_counter++;
+		else {
+			/* Unset the PSK credential to omit the extension */
+			gnutls_credentials_set(session, GNUTLS_CRD_PSK, NULL);
+		}
+	}
+
+	return 0;
+}
+
+void doit(void)
+{
+	int sret, cret;
+	gnutls_psk_server_credentials_t scred;
+	gnutls_psk_client_credentials_t ccred;
+	gnutls_certificate_credentials_t ccred2;
+	gnutls_session_t server, client;
+	/* Need to enable anonymous KX specifically. */
+	const gnutls_datum_t key = { (void *)"DEADBEEF", 8 };
+
+	struct ctx_st ctx;
+	memset(&ctx, 0, sizeof(ctx));
+
+	global_init();
+
+	gnutls_global_set_log_function(tls_log_func);
+	if (debug)
+		gnutls_global_set_log_level(9);
+
+	/* Init server */
+	assert(gnutls_psk_allocate_server_credentials(&scred) >= 0);
+	gnutls_psk_set_server_credentials_function(scred, pskfunc);
+
+	gnutls_init(&server, GNUTLS_SERVER);
+
+	assert(gnutls_priority_set_direct(
+		       server,
+		       "NORMAL:-VERS-ALL:+VERS-TLS1.3:-GROUP-ALL:+GROUP-X25519:+DHE-PSK",
+		       NULL) >= 0);
+
+	gnutls_credentials_set(server, GNUTLS_CRD_PSK, scred);
+	gnutls_transport_set_push_function(server, server_push);
+	gnutls_transport_set_pull_function(server, server_pull);
+	gnutls_transport_set_ptr(server, server);
+
+	/* Init client */
+	assert(gnutls_psk_allocate_client_credentials(&ccred) >= 0);
+	gnutls_psk_set_client_credentials(ccred, "test", &key,
+					  GNUTLS_PSK_KEY_HEX);
+	assert(gnutls_certificate_allocate_credentials(&ccred2) >= 0);
+
+	assert(gnutls_init(&client, GNUTLS_CLIENT | GNUTLS_KEY_SHARE_TOP) >= 0);
+
+	gnutls_session_set_ptr(client, &ctx);
+
+	cret = gnutls_priority_set_direct(
+		client,
+		"NORMAL:-VERS-ALL:+VERS-TLS1.3:-GROUP-ALL:+GROUP-SECP256R1:+GROUP-X25519:+DHE-PSK",
+		NULL);
+	if (cret < 0)
+		myfail("cannot set TLS 1.3 priorities\n");
+
+	gnutls_credentials_set(client, GNUTLS_CRD_PSK, ccred);
+	gnutls_credentials_set(client, GNUTLS_CRD_CERTIFICATE, ccred2);
+	gnutls_transport_set_push_function(client, client_push);
+	gnutls_transport_set_pull_function(client, client_pull);
+	gnutls_transport_set_ptr(client, client);
+
+	gnutls_handshake_set_hook_function(client, GNUTLS_HANDSHAKE_ANY,
+					   GNUTLS_HOOK_BOTH, hello_callback);
+
+	HANDSHAKE_EXPECT(client, server, GNUTLS_E_AGAIN,
+			 GNUTLS_E_INSUFFICIENT_CREDENTIALS);
+
+	assert(ctx.hrr_seen != 0);
+
+	gnutls_bye(client, GNUTLS_SHUT_WR);
+	gnutls_bye(server, GNUTLS_SHUT_WR);
+
+	gnutls_deinit(client);
+	gnutls_deinit(server);
+
+	gnutls_psk_free_server_credentials(scred);
+	gnutls_psk_free_client_credentials(ccred);
+	gnutls_certificate_free_credentials(ccred2);
+
+	gnutls_global_deinit();
+	reset_buffers();
+}
--- a/meta/recipes-support/gnutls/gnutls_3.8.4.bb
+++ b/meta/recipes-support/gnutls/gnutls_3.8.4.bb
@@ -32,6 +32,7 @@ SRC_URI = "https://www.gnupg.org/ftp/gcrypt/gnutls/v${SHRT_VER}/gnutls-${PV}.tar
           file://3e94dcdff862ef5d6db8b5cc8e59310b5f0cdfe2 \
           file://CVE-2025-32988.patch \
           file://CVE-2025-32990.patch \
+           file://CVE-2025-6395.patch \
           "

 SRC_URI[sha256sum] = "2bea4e154794f3f00180fa2a5c51fe8b005ac7a31cd58bd44cdfa7f36ebc3a9b"