From 34d0f5cb93680a5286d1eb59125631ec8fd6dc81 Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tomas@openssl.org>
Date: Tue, 25 Jul 2023 15:56:53 +0200
Subject: [PATCH] dhtest.c: Add test of DH_check() with q = p + 1

This must fail with DH_CHECK_INVALID_Q_VALUE and
with DH_CHECK_Q_NOT_PRIME unset.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21551)

---
 test/dhtest.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/test/dhtest.c b/test/dhtest.c
index 00b3c47101..d7e10ebda9 100644
--- a/test/dhtest.c
+++ b/test/dhtest.c
@@ -123,6 +123,15 @@ static int dh_test(void)
     /* check whether the public key was calculated correctly */
     TEST_uint_eq(BN_get_word(pub_key2), 3331L);
 
+    if (!TEST_ptr(BN_copy(q, p)) || !TEST_true(BN_add(q, q, BN_value_one())))
+        goto err3;
+
+    if (!TEST_true(DH_check(dh, &i)))
+        goto err3;
+    if (!TEST_true(i & DH_CHECK_INVALID_Q_VALUE)
+        || !TEST_false(i & DH_CHECK_Q_NOT_PRIME))
+        goto err3;
+
     /* Modulus of size: dh check max modulus bits + 1 */
     if (!TEST_true(BN_set_word(p, 1))
             || !TEST_true(BN_lshift(p, p, OPENSSL_DH_CHECK_MAX_MODULUS_BITS)))
@@ -134,6 +143,9 @@ static int dh_test(void)
     if (!TEST_false(DH_check(dh, &i)))
         goto err3;
 
+    /* We'll have a stale error on the queue from the above test so clear it */
+    ERR_clear_error();
+
     /*
      * II) key generation
      */
-- 
2.27.0

