Fix f284 harden wc_FreeRsaKey

Author: embhorn

wolfcrypt/src/rsa.c

@@ -564,27 +564,17 @@ int wc_FreeRsaKey(RsaKey* key)
 #endif
 
 #ifndef WOLFSSL_RSA_PUBLIC_ONLY
-    if (key->type == RSA_PRIVATE) {
+    /* Always forcezero private key fields, since they may contain residual
+     * sensitive data even when key->type is not RSA_PRIVATE (e.g., after a
+     * partial key decode failure). */
 #if defined(WOLFSSL_KEY_GEN) || defined(OPENSSL_EXTRA) || !defined(RSA_LOW_MEM)
-        mp_forcezero(&key->u);
-        mp_forcezero(&key->dQ);
-        mp_forcezero(&key->dP);
+    mp_forcezero(&key->u);
+    mp_forcezero(&key->dQ);
+    mp_forcezero(&key->dP);
 #endif
-        mp_forcezero(&key->q);
-        mp_forcezero(&key->p);
-        mp_forcezero(&key->d);
-    }
-    else {
-        /* private part */
-#if defined(WOLFSSL_KEY_GEN) || defined(OPENSSL_EXTRA) || !defined(RSA_LOW_MEM)
-        mp_clear(&key->u);
-        mp_clear(&key->dQ);
-        mp_clear(&key->dP);
-#endif
-        mp_clear(&key->q);
-        mp_clear(&key->p);
-        mp_clear(&key->d);
-    }
+    mp_forcezero(&key->q);
+    mp_forcezero(&key->p);
+    mp_forcezero(&key->d);
 #endif /* WOLFSSL_RSA_PUBLIC_ONLY */
 
     /* public part */