[test] Make sm2_internal_test less fragile to changes in the ec module

Since these are KATs, the trailing randomness consumed by the ec module
does not really matter. So make the fake random buffer circular.

(cherry picked from commit 09736245b174a37abb87fb7ceb55462d940ff2bb)

Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/11435)

diff --git a/test/sm2_internal_test.c b/test/sm2_internal_test.c
index 952f688e8b144848283d7af830017d590075b7be..f7e4e38d033467b4b1183a77f4a50f02f10f3d75 100644 (file)
--- a/test/sm2_internal_test.c
+++ b/test/sm2_internal_test.c
@@ -32,17 +32,18 @@ static size_t fake_rand_size = 0;
 
 static int get_faked_bytes(unsigned char *buf, int num)
 {
-    int i;
-
     if (fake_rand_bytes == NULL)
         return saved_rand->bytes(buf, num);
 
-    if (!TEST_size_t_le(fake_rand_bytes_offset + num, fake_rand_size))
+    if (!TEST_size_t_gt(fake_rand_size, 0))
         return 0;
 
-    for (i = 0; i != num; ++i)
-        buf[i] = fake_rand_bytes[fake_rand_bytes_offset + i];
-    fake_rand_bytes_offset += num;
+    while (num-- > 0) {
+        if (fake_rand_bytes_offset >= fake_rand_size)
+            fake_rand_bytes_offset = 0;
+        *buf++ = fake_rand_bytes[fake_rand_bytes_offset++];
+    }
+
     return 1;
 }
 
@@ -175,8 +176,7 @@ static int test_sm2_crypt(const EC_GROUP *group,
 
     start_fake_rand(k_hex);
     if (!TEST_true(sm2_encrypt(key, digest, (const uint8_t *)message, msg_len,
-                               ctext, &ctext_len))
-            || !TEST_size_t_eq(fake_rand_bytes_offset, fake_rand_size)) {
+                               ctext, &ctext_len))) {
         restore_rand();
         goto done;
     }
@@ -296,8 +296,7 @@ static int test_sm2_sign(const EC_GROUP *group,
     start_fake_rand(k_hex);
     sig = sm2_do_sign(key, EVP_sm3(), (const uint8_t *)userid, strlen(userid),
                       (const uint8_t *)message, msg_len);
-    if (!TEST_ptr(sig)
-            || !TEST_size_t_eq(fake_rand_bytes_offset, fake_rand_size)) {
+    if (!TEST_ptr(sig)) {
         restore_rand();
         goto done;
     }