memset 0 the temp contexts

src/internal.c

@@ -12372,6 +12372,7 @@ static int BuildMD5(WOLFSSL* ssl, Hashes* hashes, const byte* sender)
 #else
     wc_Md5  md5[1];
 #endif
+    XMEMSET(md5, 0, sizeof(wc_Md5));
 
     /* make md5 inner */
     ret = wc_Md5Copy(&ssl->hsHashes->hashMd5, md5);
@@ -12417,6 +12418,7 @@ static int BuildSHA(WOLFSSL* ssl, Hashes* hashes, const byte* sender)
 #else
     wc_Sha  sha[1];
 #endif
+    XMEMSET(sha, 0, sizeof(wc_Sha));
     /* make sha inner */
     ret = wc_ShaCopy(&ssl->hsHashes->hashSha, sha); /* Save current position */
     if (ret == 0)
@@ -23926,6 +23928,7 @@ static int BuildMD5_CertVerify(const WOLFSSL* ssl, byte* digest)
 #else
     wc_Md5  md5[1];
 #endif
+    XMEMSET(md5, 0, sizeof(wc_Md5));
 
     /* make md5 inner */
     ret = wc_Md5Copy(&ssl->hsHashes->hashMd5, md5); /* Save current position */
@@ -23969,6 +23972,7 @@ static int BuildSHA_CertVerify(const WOLFSSL* ssl, byte* digest)
 #else
     wc_Sha  sha[1];
 #endif
+    XMEMSET(sha, 0, sizeof(wc_Sha));
 
     /* make sha inner */
     ret = wc_ShaCopy(&ssl->hsHashes->hashSha, sha); /* Save current position */

src/tls13.c

@@ -11982,6 +11982,8 @@ static int ExpectedResumptionSecret(WOLFSSL* ssl)
     Digest      digest;
     static byte header[] = { 0x14, 0x00, 0x00, 0x00 };
 
+    XMEMSET(&digest, 0, sizeof(Digest));
+
     /* Copy the running hash so we can restore it after. */
     switch (ssl->specs.mac_algorithm) {
     #ifndef NO_SHA256

wolfcrypt/src/evp.c

@@ -5846,6 +5846,9 @@ void wolfSSL_EVP_init(void)
             if (out->pctx == NULL)
                 return WOLFSSL_FAILURE;
         }
+        /* Zero hash context after shallow copy to prevent shared sub-pointers
+         * with src. The hash Copy function will perform the proper deep copy. */
+        XMEMSET(&out->hash, 0, sizeof(out->hash));
         return wolfSSL_EVP_MD_Copy_Hasher(out, (WOLFSSL_EVP_MD_CTX*)in);
     }
     #ifndef NO_AES