Handle empty param in EVP_PKEY_CTX_add1_hkdf_info

Fixes #24130
The regression was introduced in PR #23456.

Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #24141)

(cherry picked from commit 299996f)

crypto/evp/pmeth_lib.c

@@ -1053,6 +1053,8 @@ static int evp_pkey_ctx_add1_octet_string(EVP_PKEY_CTX *ctx, int fallback,
     if (datalen < 0) {
         ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_LENGTH);
         return 0;
+    } else if (datalen == 0) {
+        return 1;
     }
 
     /* Get the original value length */

test/evp_extra_test.c

@@ -2587,6 +2587,47 @@ static int test_emptyikm_HKDF(void)
     return ret;
 }
 
+static int test_empty_salt_info_HKDF(void)
+{
+    EVP_PKEY_CTX *pctx;
+    unsigned char out[20];
+    size_t outlen;
+    int ret = 0;
+    unsigned char salt[] = "";
+    unsigned char key[] = "012345678901234567890123456789";
+    unsigned char info[] = "";
+    const unsigned char expected[] = {
+	0x67, 0x12, 0xf9, 0x27, 0x8a, 0x8a, 0x3a, 0x8f, 0x7d, 0x2c, 0xa3, 0x6a,
+	0xaa, 0xe9, 0xb3, 0xb9, 0x52, 0x5f, 0xe0, 0x06,
+    };
+    size_t expectedlen = sizeof(expected);
+
+    if (!TEST_ptr(pctx = EVP_PKEY_CTX_new_from_name(testctx, "HKDF", testpropq)))
+        goto done;
+
+    outlen = sizeof(out);
+    memset(out, 0, outlen);
+
+    if (!TEST_int_gt(EVP_PKEY_derive_init(pctx), 0)
+            || !TEST_int_gt(EVP_PKEY_CTX_set_hkdf_md(pctx, EVP_sha256()), 0)
+            || !TEST_int_gt(EVP_PKEY_CTX_set1_hkdf_salt(pctx, salt,
+                                                        sizeof(salt) - 1), 0)
+            || !TEST_int_gt(EVP_PKEY_CTX_set1_hkdf_key(pctx, key,
+                                                       sizeof(key) - 1), 0)
+            || !TEST_int_gt(EVP_PKEY_CTX_add1_hkdf_info(pctx, info,
+                                                        sizeof(info) - 1), 0)
+            || !TEST_int_gt(EVP_PKEY_derive(pctx, out, &outlen), 0)
+            || !TEST_mem_eq(out, outlen, expected, expectedlen))
+        goto done;
+
+    ret = 1;
+
+ done:
+    EVP_PKEY_CTX_free(pctx);
+
+    return ret;
+}
+
 #ifndef OPENSSL_NO_EC
 static int test_X509_PUBKEY_inplace(void)
 {
@@ -5385,6 +5426,7 @@ int setup_tests(void)
 #endif
     ADD_TEST(test_HKDF);
     ADD_TEST(test_emptyikm_HKDF);
+    ADD_TEST(test_empty_salt_info_HKDF);
 #ifndef OPENSSL_NO_EC
     ADD_TEST(test_X509_PUBKEY_inplace);
     ADD_TEST(test_X509_PUBKEY_dup);