Align math with t1_enc.c

suggested by jsing on review

1 files changed, 8 insertions, 6 deletions

diff --git a/src/lib/libcrypto/kdf/tls1_prf.c b/src/lib/libcrypto/kdf/tls1_prf.c
index e28962da2e..afc629b708 100644
--- a/src/lib/libcrypto/kdf/tls1_prf.c
+++ b/src/lib/libcrypto/kdf/tls1_prf.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: tls1_prf.c,v 1.34 2024/07/09 17:35:55 tb Exp $ */
+/*      $OpenBSD: tls1_prf.c,v 1.35 2024/07/09 17:44:18 tb Exp $ */
 /*
  * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL project
  * 2016.
@@ -265,23 +265,25 @@ tls1_prf_alg(const EVP_MD *md,
     unsigned char *out, size_t out_len)
 {
         unsigned char *tmp;
+        size_t half_len;
         size_t i;
 
         if (EVP_MD_type(md) != NID_md5_sha1)
                 return tls1_prf_P_hash(md, secret, secret_len, seed, seed_len,
                     out, out_len);
 
-        if (!tls1_prf_P_hash(EVP_md5(),
-            secret, secret_len / 2 + (secret_len & 1),
-            seed, seed_len, out, out_len))
+        half_len = secret_len - secret_len / 2;
+        if (!tls1_prf_P_hash(EVP_md5(), secret, half_len, seed, seed_len,
+            out, out_len))
                 return 0;
 
         if ((tmp = calloc(1, out_len)) == NULL) {
                 KDFerror(ERR_R_MALLOC_FAILURE);
                 return 0;
         }
-        if (!tls1_prf_P_hash(EVP_sha1(), secret + secret_len / 2,
-            secret_len / 2 + (secret_len & 1), seed, seed_len, tmp, out_len)) {
+        secret += secret_len - half_len;
+        if (!tls1_prf_P_hash(EVP_sha1(), secret, half_len, seed, seed_len,
+            tmp, out_len)) {
                 freezero(tmp, out_len);
                 return 0;
         }