Add Free(dst) + XMEMSET before XMEMCPY in all wc_ hash Copy functions (MD5, SHA, SHA2, SHA3, SHAKE) and add copy cleanup tests to prevent resource leaks when copying into previously-used contexts.

Author: night1rider

wolfcrypt/src/md5.c

@@ -537,6 +537,11 @@ int wc_Md5Copy(wc_Md5* src, wc_Md5* dst)
     if (src == NULL || dst == NULL)
         return BAD_FUNC_ARG;
 
+    /* Free dst resources before copy to prevent memory leaks (e.g.,
+     * hardware contexts). XMEMCPY overwrites dst. */
+    wc_Md5Free(dst);
+    XMEMSET(dst, 0, sizeof(wc_Md5));
+
     XMEMCPY(dst, src, sizeof(wc_Md5));
 
 #if defined(WOLFSSL_ASYNC_CRYPT) && defined(WC_ASYNC_ENABLE_MD5)

wolfcrypt/src/sha.c

@@ -1175,6 +1175,7 @@ int wc_ShaCopy(wc_Sha* src, wc_Sha* dst)
     /* Free dst resources before copy to prevent memory leaks (e.g., msg
      * buffer, W cache, hardware contexts). XMEMCPY overwrites dst. */
     wc_ShaFree(dst);
+    XMEMSET(dst, 0, sizeof(wc_Sha));
 
     XMEMCPY(dst, src, sizeof(wc_Sha));
 

wolfcrypt/src/sha256.c

@@ -2585,6 +2585,7 @@ int wc_Sha224_Grow(wc_Sha224* sha224, const byte* in, int inSz)
         /* Free dst resources before copy to prevent memory leaks (e.g., msg
          * buffer, W cache, hardware contexts). XMEMCPY overwrites dst. */
         wc_Sha224Free(dst);
+        XMEMSET(dst, 0, sizeof(wc_Sha224));
 
         XMEMCPY(dst, src, sizeof(wc_Sha224));
 
@@ -2735,6 +2736,7 @@ int wc_Sha256Copy(wc_Sha256* src, wc_Sha256* dst)
     /* Free dst resources before copy to prevent memory leaks (e.g., msg
      * buffer, W cache, hardware contexts). XMEMCPY overwrites dst. */
     wc_Sha256Free(dst);
+    XMEMSET(dst, 0, sizeof(wc_Sha256));
 
     XMEMCPY(dst, src, sizeof(wc_Sha256));
 

wolfcrypt/src/sha3.c

@@ -1306,6 +1306,11 @@ static int wc_Sha3Copy(wc_Sha3* src, wc_Sha3* dst)
     ret = 0; /* Reset ret to 0 to avoid returning the callback error code */
 #endif /* WOLF_CRYPTO_CB && WOLF_CRYPTO_CB_COPY */
 
+    /* Free dst resources before copy to prevent memory leaks (e.g.,
+     * hardware contexts). XMEMCPY overwrites dst. */
+    wc_Sha3Free(dst);
+    XMEMSET(dst, 0, sizeof(wc_Sha3));
+
     XMEMCPY(dst, src, sizeof(wc_Sha3));
 
 #if defined(WOLFSSL_ASYNC_CRYPT) && defined(WC_ASYNC_ENABLE_SHA3)

wolfcrypt/src/sha512.c

@@ -2252,6 +2252,7 @@ int wc_Sha512Copy(wc_Sha512* src, wc_Sha512* dst)
     /* Free dst resources before copy to prevent memory leaks (e.g., msg
      * buffer, W cache, hardware contexts). XMEMCPY overwrites dst. */
     wc_Sha512Free(dst);
+    XMEMSET(dst, 0, sizeof(wc_Sha512));
 
     XMEMCPY(dst, src, sizeof(wc_Sha512));
 #ifdef WOLFSSL_SMALL_STACK_CACHE
@@ -2694,6 +2695,7 @@ int wc_Sha384Copy(wc_Sha384* src, wc_Sha384* dst)
     /* Free dst resources before copy to prevent memory leaks (e.g., msg
      * buffer, W cache, hardware contexts). XMEMCPY overwrites dst. */
     wc_Sha384Free(dst);
+    XMEMSET(dst, 0, sizeof(wc_Sha384));
 
     XMEMCPY(dst, src, sizeof(wc_Sha384));